Replace capybara-webkit with poltergeist

capybara-webkit has a Qt dependency.
[related #315]
resolve locale conflict
remove language filtering, search by repo name
resolve admin view issue
style search button
remove puts
Merge pull request #322 from arthurnn/poltergeist

Replace capybara-webkit with poltergeist
Merge pull request #323 from despo/search-admin-projects

Search admin projects by repository name