[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.
Ah, well, I guess I'm just worrying too much then. Generally, testing on all of the mentioned versions would be nice to have, even if not really *necessary* right now, because anything that compiles with 2.064 and the latest release is very likely to also work for the intermediate versions.

The current guide line, until something unexpected happens, or until the major Linux distributions include D compilers with a later front end version, is that is should it should stay at >= 2.064. That version has fixed the most important bugs so far and since DUB isn't very meta-programming heavy, it's quite robust w.r.t. new compiler versions.