Configuration option to allow for case-sensitive tags

When the strict_case_match flag is on, LIKE queries are not used to
find_or_create tags.
Modify all_tag_counts method to avoid errors in PostgreSQL
Merge pull request #272 from franciscoguzman/master

A small fix that prevents error in PostgreSQL
Merge pull request #271 from pivotal-chelsea/strict_case_match

Configuration option to allow for case-sensitive tags
Add documentation about tagged_with owned_by feature introduced by #138.
Fix broken spec around case sensitive taggings
Fix mysql case sensitive tag generation and searching
Merge pull request #296 from bnorton/master

Fix broken spec around case sensitive taggings
Merge pull request #284 from ciastek/tagged-with-owned-by-doc

Add documentation about tagged_with owned_by feature introduced by #138.
Allow subclasses to override the tag_list methods
Include __FILE__ & __LINE__ info when generating methods
Added method to avoid name uniqueness validation (if scoped uniqueness validation needed)
avoid instance variable not initialized warnings
Replace format documentation to Markdown
Fix with downcase for multibyte charsets
Merge pull request #297 from jdelStrother/generated_methods

Allow subclasses to override the tag_list methods
Merge pull request #310 from caedes/master

Replace format documentation to Markdown
Merge pull request #306 from semanticart/master

avoid instance variable not initialized warnings
Merge pull request #304 from makaroni4/master

Added method to avoid name uniqueness validations
Update README.md