Plugin System

* New Plugin System using an Event module by @thinkclay <-- @rjmackay -- might want to check it out too.
* Moved SMS Providers to plugins
* SMS configuration in admin now pulled from plugins
Updated Submodule URL
Wrong Path to Submodule
Submodule Issues
Fixing Submodule (Part 2)
Fixing Submodule (Part 3)
Fixing Submodule (Part 4)

* git folks need to fix this submodule issue :bomb:
Missing Module in Config Load
Plugin Registration

* find out if there are any plugins in the plugins folder
* validate the plugins
* register the plugins
* added base plugin tests
* making this php 5.4 compatible only for now due to use of short array syntax in some classes
Moved SMS Provider Setup to SMS Provider

* Moved SMS Provider Setup to SMS Provider instead of root PingApp init()
Moved SMS Provider Properties to SMS Provider

* Moved SMS Provider Properties to SMS Provider instead of root PingApp
Merge pull request #63 from ushahidi/plugins-dev

Plugin System