NR-880: Task file management

Add task attachments upload.
NR-880: Task file management

Add files from media archive.
NR-881: Tasks - links management

Add task links.
NR-880: Task file management

Fix file attachment.
NR-881: Tasks - links management

Fix add link action.
Add missing return promise after rebase.
NR-882: Tasks - comments

Add comments number into task lists.
Add namespaces to angular modules.
Merge pull request #191 from petrjasek/aap

task attachments/links