Add support for require.js text plugin

[mikechambers]

We should include the require.js text plugin with Brackets. This plugin allows developers to load text files in the same way that they load other JavaScript modules.

http://requirejs.org/docs/download.html#text

Currently, if you want to use this as an extension developer, you have to include the plugin with your extension:

For example:
https://github.com/mikechambers/StringConvert

Notice that text.js is included in the project. You can then use the plugin like so:

var menuTemplate = require("text!menu.template");

Ideally, this will be included in Brackets so every extension developer doesn't have to include it.

I did a quick test and placed text.js in the brackets directory, and then tried to use it like so:

var menuTemplate = brackets.getModule("text!extensions/user/StringConvert/menu.template");

However, this generated the following error:

Uncaught Error: Module name 'text!extensions/user/StringConvert/menu.template' has not been loaded yet for context: _
http://requirejs.org/docs/errors.html#notloaded

Which I believe has something to do with the text plugin / module not being loaded yet. See the comment for the getModule definition in brackets.js

// Also store our current require.js context (the one that loads brackets core modules) so that extensions can use it
// Note: we change the name to "getModule" because this won't do exactly the same thing as 'require' in AMD-wrapped
// modules. The extension will only be able to load modules that have already been loaded once.
brackets.getModule = require;

[gruehle]

In Issue #258, @idflood proposes adding the text plugin for dialog templates. I agree this is a good idea.

We should be able to work around the AMD issue by explicitly loading text content in brackets.js

[pthiess]

Moved to the backlog: https://trello.com/c/BKQnEDRa