Accept Red Hat ARM Xcompilers in `check_deps.py`

Remove cache: Update check_deps.py

camkes/parser: add a DTBMatchQuery class

- add a DTBMatchQuery, which is currently a stub class
- the stub class is initialised with the parsed DTB from the command
line and dtb queries can be resolved with it
- however, currently all queries resolve to [""]
- remove the prior dtb option parsing, as this is now done in the
DTBMatchQuery class.

Fix licenses

Replace ghc and cabal in check_deps with stack

This also removes the need for the check_deps script to check for the
presence of haskell modules, as stack will ensure the appropriate
modules are installed before building.

Add orderedset as a dependency.

This commit cherry-picks 43459bca977709cf5e1cce178f1a2d0be332434d from
ssh://github.inside.nicta.com.au/mfernandez/project.

check_deps: Add `six` as a dependency.

This commit adds the Python 2/3 compatibility module, `six`, as a dependency.
Though this is not currently a direct dependency of the CAmkES code generator,
upcoming changes to the python-capdl module introduce a dependency on this
module.

check_deps: Add a mechanism for checking for a module with specific features.

This is for use in an upcoming commit.

check_deps: Add an exception type that can be explicitly caught.

This is not currently used, but can now be thrown from dependency checks and
then caught by corresponding code without also accidentally catching unrelated
exceptions.

Refactored parser init commit.

Add script for checking dependencies.