Added hashes and arrays as possible meta tag content

Kept normalize_open_graph for legacy purpose transforming :open_graph → :og

Added hashes as generic param content

Added array as generic param content

Added tests for new functionality

Updated documentation

Version bump to 1.3.0
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
Merge pull request by hand.
Support for user defined meta data fields.
Remove canonical from list.
Test on ruby 1.9.3, not 1.9.2
Allow arrays as a value of custom meta tags
Added documentation for custom meta tags
Version bump to 1.4.0
Added Ruby 2.0.0 to travis CI configuration
Added Matthew Callis as a contributor
Adding support for Hash inside an array.