Allow grunt 0.4 be installed

This might not be the cleanest solution as the API might break. At least
the plugin seems to work with 0.4 so I changed the version string to
allow larger versions than just 0.3.x.
Set up a small demo for testing
Allow dependencies to be defined

Note that I changed it to render using Handlebars. In addition the tool
now makes sure that globalAlias has been defined.
Allow dependencies to be overridden

This adds more flexibility to the system.
Tidy up dependency API

Now it's all within an object.
Document dependency configuration
Read template using fs.readFileSync

grunt.file.read points to the directory in which the plugin is executed,
not the plugin itself.
Set template path properly

Apparently it is possible to use grunt.file.read after all. Just needed
to set that template path correctly.
Remove extraneous ,
In case amdModuleId is not provided, skip that

Apparently RequireJS doesn't work well when empty name is provided.
Better skip that.
Add @bebraw to contributors
Merge pull request #3 from bebraw/master

Add support for dependencies