Add invite button
Merge pull request #1 from peccata/invite-button

Merged.
Refactor favicon block
Add project permissions
Update project editing action
Fix specs
Refactor ProjectsController#new
Fix gravatar's alt attribute
Restrict the list of potential task assignees to project participants
Redirect root to projects#index
Update routing specs
Update unit tests
Refactor redundant ternary if
Add tasks pagination
Merge pull request #2 from peccata/tasks-pagination
Update pagination
Add controller specs
Update controller specs
Add TaskSerializer
Fix task update logic