Allow falsy ID for plans

I encountered this issue, and saw that this was already reported in #55.
The fix I've included will solve the issue, but might impact other things, so this should be tested carefully.
Add test for plan, allow falsy id in request, add composer.phar to .gitignore
Revert weird changes
Update changed files to kind of follow zend style guide.
Merge branch 'master' of github.com:KorvinSzanto/stripe-php into KorvinSzanto-master

Conflicts:
	lib/Stripe/ApiResource.php
	lib/Stripe/Object.php
	test/Stripe/PlanTest.php
Merge branch 'KorvinSzanto-master'