1.11.0: gorush: do less copying in queueNotification (#370)

The PushNotification object is quite big (772 bytes on AMD64),
so avoid doing too many copying without a need.

Collect pointers and do copying only when sending into a channel.

Found using https://go-critic.github.io/overview#rangeValCopy-ref

Linter output:
```
$GOPATH/src/github.com/appleboy/gorush/gorush/worker.go:38:2: rangeValCopy: each iteration copies 772 bytes (consider pointers or indexing)
$GOPATH/src/github.com/appleboy/gorush/gorush/worker.go:53:2: rangeValCopy: each iteration copies 772 bytes (consider pointers or indexing)
```

Support gRPC protocol

Feature

304855c feat: support storage engine flag. (#235)
276cb49 add redis addr flag. (#236)
eb05be9 feat: add k8s config. (#237)
9a52f8f feat(grpc): initial grpc server. (#253)
41a8a60 feat(config): add grpc config. (#255)
20713be feat(grpc): add node.js example. (#260)
f482c98 feat(Makefile): add generate proto method
00ff024 feat(config): enable or disable httpd server. (#262)
a466827 support arm64 and arm docker image. (#277)
ffd5515 add healthz check (#286)
f960f94 add version handler (#287)
f3480d2 Support global ENV setting. (#293)
461a57e support Device Group HTTP POST Request (#299)
c06e819 Support new Apple Token Based Authentication (JWT) (#300)
313d74c Support get different mode of apns client in request for iOS app (#301)
a714d03 feature(server): allow to bind specific addresses (#263)

Enhance

8dcc680 move storage interface to storage folder. (#240)
115ee18 Send messages to topics for android (#296)
34588dd upgrade apns2 to 0.13 (#297)
01d545a Change Request.Header.Get to GetHeader function (#290)

update GCM to FCM

96b5fb4 Support multi-stage docker build. (#229)
77bce18 feat: upgrade gcm to fcm (#231)
14dc899 feat: check unused package (#232)

improve cli command

957db77 feat: upgrade apns2 to v0.9 (#222)
0a9a30c fix: improve cli command error. (#223)

v1.8.1

Features:

• fcdd369 feat: [ci skip] add debian/ubuntu init script. (#210)
• b6997ea feat: support sync mode for http response. (#208)
• 0c9aad5 feat: get error logs from fail notifications. (#213)

Bugs:

• 04caa04 fix: check certificate file exist. (#209)

v1.8.0: release 1.8.0

refactor

c67af96 refactor: update version name in header. (#188)
92b9da2 refactor: hash is a much faster shell-builtin alternative to which. (#192)
04ff032 refactor: update build flag for windows. (#197)
5b2b369 refactor: support AbortWithStatusJSON (#200)

feature

962c033 feat: set runtime.NumCPU() as default worker num value (#174)
3f4485e feat: Add support for the mutable-content flag (#179)
23bd0d0 feat: switch glide to govendor. (#186)
e9dc429 feat: embed code into markdown and keep everything in sync (#191)
97eae1f feat: support Automatically install TLS certificates from Let's Encrypt. (#205)

bugs

f155e20 fix: Remove unnecessary type conversions (#176)

v1.7.4

@appleboy:
73aca36 add ARCHS variable.
e5b916c fix: GOMAXPROCS set to the number of cores available in 1.5
015a23d feat: add new flag --pid
d8c4659 feat: creat pid folder automatically.
9f87268 fix: Clone tags within drone for proper version generation
cbbbc4e fix: Enforce custom LDFLAGS within makefile and add coverage command.
a669070 feat: support prometheus metric url. (#168)
9bd6886 refactor: Support empty notification for android (#170)
2a00ed7 feat: support title flag on cli (#172)

Support graceful restart & zero downtime deploy

• Support graceful restart & zero downtime deploy using facebook grace.

Fix ios example error

dfe8929 Add run time CPU count.
9595062 refactor default engine as memory.
1f404e0 fix reset color format.
1707f39 remove required field: message

Release v1.7.1

• Support Windows binary.
• Skip ANSI color commands if