add acts as taggable on keywords

add acts as taggable on keywords.changed the blog post controller to
keep track of that and changed the factories accordingly
changed js and views keywords handlers

added an autocomplete for keywords. changed the form, index, show views
so they take into account the new keywords
fixed last failing specs
made integration tests more readable

created missing method for create_blog_post_with_"something". changed
all test to take this into account. changed blog post titles names so
they're more readable
changed common helper methods

removed method missing. used the create_a_blog_post method with
arguments. it's enough to make everything more readable. created two
visit_that_page methods.
add missing tags and fix spelling error
Merge pull request #23 from xskander/feature/taggable_keywords

Feature/taggable keywords