Allow arrays as include values

This commit is the missing half of #17, "feature/dynamic_include_paths".

Allowing arrays as include path values allows include paths to be
generated at runtime, as the result of some ruby operation.

For example:

    :paths:
      :include:
        - <%= ['some_value', 'some_other_value'] %>
        - <%= `build_system_tool_returning_array_of_paths`.split("\n") %>

This allows include paths to be generated by the build tool, without
upsetting ceedling too much.
Add CEEDLING_IGNORE_SANITY_CHECK, which if defined skips test sanity check

This is required if using ceedling to run Unity's test suite, as in this
case the test counts don't match up (Unity's tests are allows to fail,
and this can be treated as a success, for example).
Merge pull request #31 from canton7/feature/dynamic_include_paths_contd

Allow arrays as include values
Merge pull request #32 from canton7/feature/ignore-sanity-check

Add CEEDLING_IGNORE_SANITY_CHECK, which if defined skips test sanity check