Allow 'system' user to modify cpufreq control files

This is needed by new CPU Settings in CMParts

Change-Id: I0ec4e0b1705670034a433df549b2895985c476af
init: provide initial pemissions for ondemand governor

also set all governor permissions a bit late

Change-Id: I5c1445b31bcaf34a535efd7438fd612ada460ea2
rootdir: Set permissions for additional interactive sysfs nodes

Change-Id: I2dbcdcc199c5f75d08e8ebf41cd6768c7648e27b
Refactor versioning

* Replace the 1-to-1 variable-to-buildtype stuff with a single
  environment variable. CM_[TYPE]=true becomes CM_BUILDTYPE=[TYPE]
* Change the placement of the extra version tag: 10.2-21234567-TYPE-model-TAG
  becomes 10.2-21234567-TYPE-TAG-model, for consistency with the rest.
  The last component of the version should always be the model.
* Add support for the SNAPSHOT build type, for use with the monthlies
* Unknown types will still fallback to UNOFFICIAL
* Accept the jenkins RELEASE_TYPE variable as an alternative to
  CM_BUILDTYPE for compatibility with older branches

Change-Id: Idf96c7ca887747a5ae49a17cf5adf642fb1d561f
Merge remote-tracking branch 'upstream/cm-10.2' into HEAD