Don't show imagery block if no imagery is available
Merge pull request #113 from pgiraud/imagery

Imagery
Changing the workflow a bit, first round
second round
Let the comment field be required.
A lot of changes
Change view name (take -> lock)
Mark task as done in two steps to keep a valid history
History of the changes
Cosmetics
Cosmetics again
Cosmetics (added icons)
Focus on the comment textarea
Fixing problem with sammy intrusive routing
Add the current tile status in the history if locked
Show the export buttons only when task is locked
Unlocks also need to be listed
Reorganizing buttons
Don't show lock button if not required. Add link to locked tile.
Show 'unlocked' in history only when no change has occured