add by_language scope to projects and users
resolve conflict
expose /language/:language and display information
resolve conflict in pull request spec
add pagination for projects on language page
add /language/:language/projects
add /language/:language/users
pull requests for a language
use helper to retrieve user count
only show PRs for current year
reuse pull_requests/index to render language prs
Merge pull request #305 from despo/add-language-page

Add language page