changed default cellID encoding and deconding strings, added hit properties

- removed clusterID field (unused/obsolete)
- increased width of sensorID field to 7bits
- added encoding string for hit sensorID and hit properties
- added hit properties string
- addresses issues #11 and #25
hitmaker now adds sensorID and properties fields

-addresses issues #11 and #25
-sensorID copied from cluster sensorID
removed commented out code from hotpixelkiller
removed obsolete CMake script for EUDAQ

- replaced linking against EUDAQ lib with separate converter processor shipping with EUDAQ
added guidelines for developers

- moved instructions from README.md to CONTRIBUTING.md
- added some further info on commit style and branching with git