Added no-self-import rule

[just-paja]

New rule checks against importing from the current file. Ref #447.

First time working with eslint rules. Please review.

[coveralls]

Coverage increased (+0.02%) to 97.662% when pulling 85b2e71 on just-paja:feature/no-self-import into 6e12c9e on benmosher:master.

[benmosher]

I think this rule should leverage the resolve infrastructure.

At least, if resolve comes back non-null, then the result should be compared with context.getFilename(). Then the resolver is responsible for things like missing extensions, aliases, linklocals, etc.

[jfmengels]

This would be a cool rule to have!
Are you still up to work on this @just-paja? No worries if you're not :)

[just-paja]

Hey, sorry all, I completely forgot about this. @jfmengels, I will happily pass this to you.

[jfmengels]

Hey, no problem ;)
Not sure if/when I'll get to this. It's up for the taking if someone wants to have a go at it.

[giodamelio]

If it's all right with everyone. I would like to take a crack at this one.

[jfmengels]

Please do @giodamelio!

[giodamelio]

Awesome, I just opened #727.