Adds support for nested partial names

[kflorence]

• Partials will be named according to their base directory, for example for a glob pattern of source/partials/**/*.hbs, a partial defined at source/partials/foo/bar.hbs would be assigned the name foo/bar.
• Also fixes throwing errors if options.data, options.helpers or options.partials are not defined.

[kflorence]

@shannonmoeller Another thing to consider would be using gulp.src (or vinyl-fs.src which is what gulp uses) instead of the current method of getting files since there is a bit of duplicated logic around paths in here otherwise and it seems cleaner to just use them instead.

[kflorence]

@shannonmoeller Is there something I can do to get this merged faster? Right now I have a local copy of this that I'm using, but it would be cleaner if I could pull it down instead.

[shannonmoeller]

This is a good change, but it doesn't entirely follow the code standards. Please join your multiple var statements into a single var block, separated by commas. It's a Crockford thing I haven't given up yet. :)

[kflorence]

@shannonmoeller cool, I will do that in a bit.

[shannonmoeller]

Published as v0.2.0!

[kflorence]

@shannonmoeller thanks :)