fixup! uBrowser: Reference EWK browser application

fixup! uBrowser: Reference EWK browser application

When /bin/sh is not bash (for example, when it's dash), trying to launch
ubrowser.sh will result in errors "pushd: not found", "popd: not found"
and such.

This is because ubrowser.sh sources build/common.sh which contains
bashisms.

This patch launches ubrowser.sh with bash, and therefore prevents those
problems.
Reviewed by: Antonio Gomes, Piotr Tworek

Change-Id: I0b51bc9695b35d11cec08fe40ef73d1941012844
Signed-off-by: Arnaud Renevier <a.renevier@samsung.com>