[mer-hybris] Skip initial update if no proximity sensor is found
[mer-hybris] Force hybris configuration if hybris libs are installed

This fixes a problem where on grouper, the configuration setting for
non-hybris setups is enabled, and therefore never updated when hybris is
installed.
[hybrisadaptor] Remove unused fields/methods in reader class
[hybrisadaptor] Simplify HybrisManager::processSample
[hybrisadaptor] Fix duplicate sensor open/close bug

The logic called sensors_open() twice, which broke accelerometer reading
on grouper. Fix this by moving the open/close handling to separate
places (openSensors() and closeSensors()) and using the device pointer
instead of a separate boolean variable to check if the device is open.

- Use device's non-NULL/NULL state as indicator for whether or
  not the sensors are opened (instead of "bool sensorsOpened")
- Make data members of HybrisManager protected by default, and
  move them all in a single spot in the declaration, so that it's
  easier to see which fields exist and the initialization order
- Proper initialization of HybrisManager members in constructor
- HybrisAdaptorReader is friend of HybrisManager (access to device)
- Make sure sensors_open() and sensors_close() are not called
  twice by removing duplicate code and using openSensors() and
  closeSensors(), which contain logic to avoid double-open
Merge pull request #32 from thp/mer-hybris-grouper

Various fixes to make mer-hybris sensors work on grouper