Started Japanese localization.

As a first step, translated basic strings.  That's easy.
Merge branch 'master' into localization-ja

Conflicts:
	res/values/strings.xml
Added new Japanese strings after merge.
Merge branch 'master' into localization-ja
Added a missing new line in About text.
Japanese translation of about text.
Convinced lint of some strings.
Merge branch 'master' into localization-ja
Translated OpenCV initializer
Merge branch 'master' into localization-ja

Conflicts:
	res/values/opencv_initializer_strings.xml
Translated "Download OpenCV" dialog title.
Merge branch 'master' into release

Conflicts:
	res/values/strings.xml
Prepare for 0.80 release.
Visits OpenCV Manager download page as a new task.
The download URI is taken from resource.

A lot of comments to OpenCV Initializer
Merge branch 'localization-ja' into release
Updated some UI strings
Convinced lint.
More updates to about text (both En and Ja.)
I forgot to commit the updated release note for 0.80. :-(
Added "shutter button" on the release note.