Clean up style and comments in modules.

We have some minor style issues in modules code. This ticket aims to clean them up.

s/template<>/template <>/
Affected files:
include/mesos/module/authenticatee.hpp
include/mesos/module/authenticator.hpp
include/mesos/module/hook.hpp
include/mesos/module/isolator.hpp
src/examples/test_module.hpp

Move { } onto the previous line in Module c-tors
Affected files:
include/mesos/module/authenticatee.hpp
include/mesos/module/authenticator.hpp
include/mesos/module/hook.hpp
include/mesos/module/isolator.hpp
src/examples/test_module.hpp

Misleading comments in test modules.
Module name is an exported symbol. Comments on module declaration should reflect this. Affected files:
src/examples/test_anonymous_module.cpp
src/examples/test_hook_module.cpp
src/examples/test_isolator_module.cpp