output the alerts in a table in the home page

In a table looks better
simplify a little the navigation

Remove the "~", make the home page be the home/index for both users and
admins and add an "admin" link for admins to view the admin page.
fix test for session controller
fix test for session controller
review style
review ui: output what others have said in show action
review ui: do not need to filter security alerts cause they are already filter and review table headers in home
fix#9: list the gems that have issues in the result action for the ruby_application controller
do not install development gems in travis
fix a typo in travis.yml
replace sqlite by pg
set ruby to 1.9.3 in Gemfile
configure postgresql in all environments
add heroku integration gem
add heroku integration gem
fix db/schema to use pg
add heroku instructions
update heroku git instructions
add .env to .gitignore
add unicorn as web server