This struct and type contains the logic for routes contained previously
in the Router API and be used to help choose which handler to use.

Used for interacting with content store's postgres db.

This implements the logic to query the content store and populate the
triemux.

This makes a connection pool to the database url specified with he env
var CONTENT_STORE_DATABASE_URL.

This provides a simple feature flag to turn off routing using content
store and allows us to canary a percentage of requests to use the
content store mux. A value of 0.0 will switch off the feature entirely
and prevent the Router from trying to create a connection pool.

This uses that the CsMuxSampleRate to controller the percentage of
requests served by the mux built using the content store data.

This adds a helper function to update csmux with a new version
containing updated routes.

This fixes a golint error.

This is a fail safe in-case the listen/notify mechanism.

This ensures we don't reload more than we need to. If a notification
already exists to reload, then we don't need to send another
notification, as all updates will be captured in the next reload.

This are stylistic changes and missing test for invalid json in the
details column.