Enable command-line options for unit tests.

Enable command-line options for unit tests.

Add a simple framework for easily parsing command-line options in unit
tests.  Use the framework to add a -seldebug option for the selection
tests to make it easier to debug issues in failing tests.  Adjusted the
initialization code for testutils to go through a single function.
Also fixed a noticed issue in the command-line parser that made it
impossible to pass in negative numbers.

Change-Id: Idb17a44d3a2669a91cf077acc99b3475d2c251a0