Refactor System Tests

This patch,
1. Renames 'System Tests' to 'Functional Tests'.
2. Reduces LOC by using ddt.
3. Removes test dependencies & the numbering convention used earlier.
4. Re-organizes the test suite structure.

blueprint refactor-system-tests

Change-Id: Ife236abf867b678beb72ea3a26a06d895ed8ad4b
Merge "Refactor System Tests"