replace sqlite3 with postgres in all environments and travis-ci
Merge remote-tracking branch 'vmw-tmpst/master' into switch_to_postgres

Conflicts:
	Gemfile
fix errors in Gemfile
Merge pull request #49 from whywhy36/switch_to_postgres

replace sqlite3 with postgres in all environments and travis-ci
add extra environment 'ci' to do ci job in travis
fix build_ci script
set the RAILS_ENV to ci
Merge pull request #52 from whywhy36/switch_to_postgres

Must be modified in one elegant way!