Issue #232, initial similarity calculation algorithm.

Based on Jaccard similarity of the tag sets only. Al bakeya tatba3.
Calculate idea similarity on save.
Add similar_ideas relation to the Idea model.
Add default ordering to the Similarity model.

order by similarity
Add similar ideas partial.
Merge master
Fix error in ideas.css
Remove empty line in edit.html.erb
Merge master into improving_idea_submission_form
Fix Gemfile
Turn on library autoloading
Revamp the similarity index algorithm.
Tune the similarity calculation model.

Add lambda values to calculate functions of each component.
SimilarityEngine: tune model again and load necessary idea data on creation.
SimilarityEngine: add tests

100% coverage
SimilarityEngine: add manual rebuild routine.

Automatic calculation should be turned off during DB population or it will take
forever.
Turn off similarity calculation during db:populate
SimilarityEngine: remove stale comment.
Merge branch 'master' of github.com:DevYah/coolsoft-13 into C1_mnzaki_#232_similar_ideas

Conflicts:
	Idearator/app/models/idea.rb
SimilarityEngine: do not add an idea as a similar idea to itself