IPC unit tests and testing framework improvements

IPC unit tests and testing framework improvements

[Feature]       1. IPC unit tests
                2. Cleaner args parsing in vsm_launch_test.py
                3. Options to launch a test under custom tools
[Cause]         1. N/A
                2. Bugs when launching with external tool
                3. Ability to launch any GDB front-end
[Solution]      1. N/A
                2. Use list instead of string in Popen
                3. Two new command line options
[Verification]  Build, install run tests. Try to run single test with
                a fixture, for example:
                vsm_launch_test.py vasum-server-unit-tests -t \
                  'IPCSuite/Restart<15ThreadedFixture>'
                To test running with --gdb option run test logged as
                root or use sudo with -E option in order to preserve
                environment.

Change-Id: Icb09c0abed5c671c86a8c85d2aab1aa2b2412d29