IE extension: ~90% of commonly shared code with chrome

Added classes:

Scrive.Platform.HttpRequest 	ScriveIEHttpRequest.js
	get/put
	sendPDF
	PrintToEsign

Scrive.IE.i18n		ScriveIEi18n.js
	getMessage
	init		autodetect system language and fetch JSON locale from the server

Scrive.Platform.BrowserUtils 	ScriveIEBrowserUtils.js
	getExtensionVersion returns activeXObj.version

x refactor xmlhttpreq out of OAuth.js, Scrive.Contscript popup.js synced with Chrome

ScriveMain.js is now initialization point for IE

ScriveIELocalStore.js and ScriveIEHttpRequest.js now have callbacks.

  'ie/ScriveIEi18n.js',
  'ie/ScriveIEBrowserUtils.js',

ScriveIELoader.js
	new loader event tag.onload replaces tag.onreadystatechange for IE11

x refactor xmlhttpreq out of Mixpanel
       "libs/mixpanel_init.js",