ready for sensitivity plots

Lots of improvements and bug fixes, some highlights listed below.

Major framework changes:

• removed astropy_helpers and ctapipe_extras sub-repos (the latter is now a seprate module)
• improved setup, versioning, and package system
• improved documentation
• working unit tests
• support for travisCI documentation builds
• simplified instrument module
• faster and more unified CameraGeometry, with support for cameras in FITS files
• basic provenance system to record input/output/parameter metadata
• improved coordinate systems
• event-wise HDF5 table io
• improved camera and array displays
• ctapipe-dump-instrument tool

Major algorithm changes:

• complete Muon analysis
• complete Hillas reconstruction (HillasReconstructor)
• energy estimation with machine learning
• ImPACT reconstruction and fast table interpolation
• cleaned up ChargeExtractors and WaveFormCleaners
• simplified calibration (and added CameraCalibrator helper)