External installation

External installation

This patch implements installation of package in external sd card storage.
Tpk and wgt applications may declare preference of being installed on external
storage. If so and space requirement is satisified then their resource directory
is installed in sd card with use of app2sd API.

Following patchsets should be submitted together:
 - https://review.tizen.org/gerrit/61678
 - https://review.tizen.org/gerrit/61679
 - https://review.tizen.org/gerrit/61680

Verify by:
 - running smoke tests,
 - running installation, update, deinstallation for package that prefers external
   installation (SD card must be inserted).

Requires:
 - https://review.tizen.org/gerrit/#/c/64796/

Change-Id: I174c14ddfb48dc2bc1a5935c3b4799abd7f26332