tc: updated run_docker.sh

it includes:
 - Avoiding package installation all over again while re-building
   the docker image if there is no change in the requirements.sh
 - Installation of only newly added packages while re-building
   the docker image if there is change in requirements.sh.

Signed-off-by: Rupinderjit Singh <rupinderjit.singh@arm.com>
Change-Id: If96a9729ea4eae4b7d4d8aeb551ad42c75fd9426