Make support for default GET arguments in AdhocBrowserPool

[wzin]

Overview:

This ticket is the other half of the work that's speced out here: https://github.com/EndPointCorp/lg_chef/issues/1273

Requirements:

• Make it possible to provide list of GET arguments that will be passed to each and every instance of the AdhocBrowser
• make sure that GET args are unique
• make it be a param

[minshallj]

arguments should make their way into /var/www/lg/lg-head.xml under /global_get_args/* or something like that. Then adhocBrowserPool should grab all key/values and append <url>?<key1>=<val1>&<key2>=<val2> etc

[minshallj]

test w/ tactile first please to make sure this is even possible.

[axisofentropy]

Another use case for this: Right now when launching Gigapixel, GET parameters for the portal-launcher Quick Menu don't get passed into the URL. Other applications use an intermediate "launcher" HTML page, but Gigapixel does not (and probably should not) so we need another way to get those passed.