Tidy up .gitignore

Based on https://github.com/github/gitignore/blob/master/Ruby.gitignore
Move SQLite db to the tmp directory
move test Gemfiles into /spec/support
Let's clean the database with truncation
Update gemfiles to point to the gemspec
Make sure the tmp dir has been created
Merge remote-tracking branch 'origin/master' into clean_up_specs

Conflicts:
	spec/spec_helper.rb
Newer versions of SQLite have a different error message

Match on the similar part of the message
Merge pull request #68 from envato/clean_up_specs

Clean up specs