MCP3008 provider
- added new provider for MCP3008 10bit ADC
- added test cases using jmockit
- adding new maven dependencies to jmockit, junit, log4j and commons
  logging
- added test resource for log4j
- introducing the pins as enumeration to have more safe way to assign
  PINs
Merge branch 'feature/mcp3008' of https://github.com/PoJD/pi4j into PoJD-feature/mcp3008
dropped logging impl; we need to choose a single consistent logger interface for the whole project. (See #17)
modified MCP3008Pin to be more consistent with other expansion interfaces
Merge branch 'PoJD-feature/mcp3008' into develop