Merge pull request #1 from ychubachi/master

Please merge this
Addition of env. variables for trabis
Merge branch 'master' of github.com:ryuichiueda/sinatra_enpit
Addition of rake to Gemfile
Added an empty Rakefile
Addition of setting of PostgreSQL thought it is not used
Addition of database.yml.travis though it is not used
Removal of database configs
Add rack-test gem
Add rake and minitest into Gemfile
Create Test task and the test.