Clean up Votes controller specs

Remove unecessary variables and fix expectations of each test.
Add 'database_cleaner' gem to test environment

Use the 'database_cleaner' gem to clean the postgres database after specs.
Use 'database_cleaner' gem to clean test database

Use the gem to clean out data created by test specs if any is left over
afterwards. The gem covers some of the cleaning RSpec misses, such as
records created in before(:all) blocks. These records will sometimes be
missed after each spec and left in the database causing other tests to
fail. Using this gem configuration will completely clean any tables of
these leftover records.
Expect Votes partial to be rendered

Expect a partial containing voting buttons to be rendered when the
partial 'votes/vote' is requested.
Add a '_vote' partial containing vote buttons

Create a partial containing buttons for voting on an idea and changing
or removing the vote once it has been created.
Render '_votes' partial and idea's rating

Render a partial for voting and the idea's rating in the 'idea/show'
template.
Fix pending IdeasController test messages
Set '@user_vote' variable in IdeasController

Set a variable containg the record of a user's vote on an idea if the
current user has voted on the idea who's view is being rendered. Check
to see if a user is signed in first, then if they have voted on the
idea in the first place before trying to retrieve it.
Fix 'ideas/show' template

Execute the 'if' statement, don't render the output.
Add some (breaking) Vote feature specs

Create some feature specs for testing voting functionality. Currently,
tests break for one reason or another when all four are enabled.
One issue is that these specs expect to be executed in a particulr
order, which they shouldn't be so they'll have to be adjusted.
Additionally, the votes controller appears to be behaving a little
strangely. The view rendered after voting doesn't always appear to be
up to date and needs to be refreshed.

TODO:
   * Fix Votes controller/Idea vote counting to render correct content
   * Fix Vote feature specs to perform the correct actions for testing