Use POST for subscribing/unsubscribing from forum topics.

Fixes #522
Implement 'Nil User' pattern to deal with deleted users

Potential fix for #427
Use Workflow 1.0.0 and change update_attribute calls to update_column calls.

There's also been a change to use Workflow's hook methods, so that Post and Topic both have their own #approve methods now.

Conflicts:
	forem.gemspec
Add missing translation keys and lookups

Fixes #523
Bump to kaminari 0.15.1
Use Rails4 branch by default
Add Rails 3 install instructions to README
Add real friendly_id dependency
Update Forem::Forum order in the default_scope

Fix to avoid ambiguous column errors

Fixes #533
Fixes #529
Fix failing test because user is being rendered twice

Fix test for all.to_sql

Fix test for all.to_sql

Bring mysql2 back to Gemfile

Fix test for all.to_sql

Use dot instead of quotes to make sure the test passes

2 spaces for indentation
Merge pull request #535 from bodrovis/fix_user_being_rendered_twice

Fix failing test because user is being rendered twice
Merge remote-tracking branch 'forem/rails4' into rails4