camkes/alltests.py: add verbosity argument

camkes: rewrite alltests.py to use unit tests

Prior to this change, alltest.py ran indepedant test runners from each
package. This has several downsides: tests could easily be missed (if
the individual test runner did not include the correct classes) and
tests were parallelised poorly (only on a per package test run basis).

This change rewrites the script to use unittest dynamic test discovery
features and concurrentTestSuite, which allows tests to be discovered as
long as they are in a valid module considered by the script (modules
are listed alltests.py help) and tests can run highly concurrently (this
takes the test run time from 1 minute to 7s on my machine).

The script still allows subsets of the tests to be run by specifying the
list of packages to be tested. As before, all packages are tested if no
package is specified.

camkes: obtain capdl-python from PYTHONPATH

Prior to this change, capdl-python was passed in as an argument to the
rest script and dynamically installed in the environment. A downside is
that this means no camkes packages can be imported into the test runner
that need capdl, as it is not in the python path of the test runner.

This change makes the script expect capdl to be in the PYTHONPATH, for
future changes which require camkes modules to be imported.

Remove cache: Remove tests and usage of cache and accelerator

Since the cache is removed, there's no point to test it.

alltests.py: python3 compatibility

sys.maxint does not exist in python3. Stack overflow suggests that
sys.maxsize or float("inf") could be a solution, but passing these
causes an exception later down the stack that the value is too big for a
timeout. Work around this by just adding a big number.

tests: take capdl path as argument

Fix licenses

Refactored parser init commit.