Fix permissions in some test and source files.

Remove the executable bit that should have never been set in the first
place.
Split xwalkctl and pkgcmd backend

All the application management (app un/installation) logic is now removed
from it 'xwalkctl'- it is only responsible for XWalk common settings,
like setting of debugging port.

The application management is moved to a separate target: xwalk_backend.
The wrapping script is removed as well.

BUG=XWALK-2671
BUG=XWALK-2579
Merge pull request #2502 from pozdnyakov/split_xwalkctl_and_pkg_backend

Split xwalkctl and pkgcmd backend
Merge pull request #2496 from rakuco/remove-executable-perms

Fix permissions in some test and source files.
Bump version to 10.38.225.0