Merging ServletBasedEnvironment with DefaultEnvironment

As described in #811.

VRaptor was designed to works with Servlet environment, so there is no reason to `DefaultEnvironment` lives without `ServletBasedEnvironment`. Almost all tests inside `DefaultEnvironmentTest` is duplicated in `ServletBasedEnvironmentTest` too.

So with this pull request I merged both classes, and did a some refactor to make some improvements like loading properties file without recreating unnecessary instances. All instances creation are moved to `PostConstruct` method, and more.
Sorry for flooding :). I'm not too expert in CDI like you @Turini. So thanks to help me about this case. I'll do some tests in my application tonight to understand this behavior, because I really don't know if my idea works as expected for all cases.

Because this pull request makes a big change, we can discuss more before merge, to avoid breaks compatibility.