* clean up plugins GoDoc:
- eliminate plugin.NewBlankContext() as unnecessary
- export ValidIdRegex as a string vs. the less readable var
- add/update various documentation strings
- hide everything by default, except where used by client plugins or the mattermost-server. The exception to this rule are the `*(Args|Returns)` structs which must be public for go-plugin, but are now prefixed with `Z_` with a warning not to use.
- include a top-level example to get plugin authors started
This is not a breaking change for existing plugins compiled against
plugins-v2.
* remove commented out ServeHTTPResponseWriter
* update examples to match developer docs
* add missing plugin/doc.go license header
update api mocks
Generated new hooks
ChannelHasJoinedChannel Implementation
User Left Team/Channel Hook; User Joined Team Hook Implementation
Update RPC Client and Mocks
gofmt
go tests fix
Add Config API Methods
codegne
Add Channel Has Been Created Hook
Fix ChannelHasBeenCreated hook
fix missing context param
fix duplicate hooks; remove redudandcy
* Adding blank request context to plugin hooks for future use.
* Rename RequestContext to Context
* Adding context to ServeHTTP and ExecuteCommand
* Fixing import cycle in test.
