Add AppVeyor support (Windows CI builds)

[PeterBowman]

Blocked by #87.

[PeterBowman]

This is currently WIP: https://ci.appveyor.com/project/asrob-uc3m/robotdevastation.

[PeterBowman]

Mostly done, all libraries + tests compile and run successfully. Additionally, this issue resulted in adding a new repo to asrob-uc3m: https://github.com/asrob-uc3m/ZBar. There is one caveat about AppVeyor I should remark here: we are allowed to run only one job simultaneously (on the other hand, Travis CI seems to be limited by the system load). This is especially noticeable when starting multiple jobs per build and ultimatelly may result in much larger delays in code deploy than we were used to with Travis.

• Currently, jobs take about 7 minutes to complete if ACE is stored in the cache (~10 min otherwise). I'm going to place YARP in the cache as well and cut this down to about 5 minutes.
• Dependencies along with their release version are listed in the .appveyor.yml file. The policy I would like to adopt is to compile always against the latest releases (this has to be duly noted in the user manual).
• Cache storage is automatically invalidated whenever .appveyor.yml changes.
• Three worker images are available: https://www.appveyor.com/docs/build-environment/. I'm going to migrate to VS 2015 (currently using VS 2013) due to its availability of installed software. VS 2017 should be considered in the near future.
• Builds will encompass two architectures (Win32 and x86) and only one configuration (Release) in order to keep things simple (see first paragraph) and support multiple-architecture deploys at the same time.

[PeterBowman]

Done at 3a7b908.