Merge pull request #10 from parroit/master

Add reference to gulp plugin.
Add support for external modules (not to be bundled but used as UMD deps).

* Added option for external modules hash with optional separate AMD / global names. Fixes #5.
* Add proper source map comparison (check whether all the mappings still work).
Added support for external modules in command line parameter.

Fixes #5.
Added command-line example.
Update README.md
Update README.md
Update README.md
Upgraded estemplate and using new types of substitutions.
Remove some builders in favor of estemplate substitutions.
Added support for custom file reader implementations.

Now plugins can pass in own implementation of getFileStream/getFileContents/getFileAST.
Cleanup and dependency upgrade.
Update README.md
Added `transformAST` method.
add index.js to file path if module path refer to a folder