Removed test and doc from target all in Makefile

When running tests with [erlang.mk](https://github.com/extend/erlang.mk) and using [meck](https://github.com/eproxus/meck) as a test dependency, all of **meck**'s tests are always run before the project's, which consumes some considerable time when running tests. This is due to the fact that **erlang.mk** executes ``make`` for each dependency when building the tests and the ``all`` target in the **meck**'s ``Makefile`` includes the target ``test``.