[WIP] Create tests for basic dub usage + bump compiler version to 2.065.0

So this was more useful than I previously thought...

It revealed 2 issues related to dynamic libraries, which is why it can't be merged yet also. The first one is #352 which prevent building dynamic libraries right now. The second one is that dependencies to dynamicLibraries used to trigger a this-is-not-implemented-yet error. Now, the dependency is just converted to a "library" dependency, which is a staticLibrary. Thanks to #352 I noticed it.

The code for .travis.yml seems to be the same than the one I wrote for vibe.d. Unfortunately, it suffers the same problem vibe.d had (aka, it should "exit 1" instead of "break"). And it was testing the "dub" in the system path (so the downloaded one, which is currently 0.7.21) anyway. So the unittests are useless ATM.

Lastly, why is "library" intended for ? I think it would be *super* nice to have a package that's marked as "library" build both dynamic and static library. This way, one can depend on a package either by library (which should be dynamicLibrary), by staticLibrary or dynamicLibrary.
This was deliberately set to 2.064 to guarantee that the code still compiles with current the LDC and GDC. Ideally it would test with both, 2.064 and 2.06(5/6), but the current installation procedure is already stressful enough for the CI servers, IMO.