Merge pull request #31 from guillelopez/master

Added hashes and arrays as possible meta tag content
Refactored custom Hash trees processing
Only add OpenGraph tags if content is provided

Merge pull request #29 from jazzgumpy/master

Conflicts:
	lib/meta_tags/view_helper.rb
Don't include robots/noindex/nofollow if content == false

Signed-off-by: Holger Frohloff <holger.frohloff@gmail.com>
Use HashWithIndifferentAccess to store meta tags, which will allow to use both symbols and strings as tag names

Closes issue #26
Don't insert (unneeded) title tag if no title is present
Added specs for blank title, description, keywords
Updated changelog
Updated contributors list