Fix for SW-112:
- moteState component dispatches an infoDagRoot signal only when he mote switches to being a DAGroot.
- RPL module only registers when not registered yet. Unregisters from previous if dagroot changes
- eventBusClient break when finds callback
- small code cleanup
SW-112. Addressing suggestions from https://openwsn.atlassian.net/browse/SW-112?focusedCommentId=14501&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14501.
SW-112. Don't send DIOs after unregister DAG root
Merge pull request #63 from kb2ma/develop_SW-112

SW-112. Don't send DIOs after unregister DAG root
Merge pull request #62 from openwsn-berkeley/develop_SW-112

Fix for SW-112:
SW-130. Distribute simulation module variants, and select at install time

Changes include:
* Added --simhost option for SCons copy-simfw target. Copies current
  openwsn-fw simulation firmware to a 'linux' or 'windows' subdirectory of
  'sim_files' Renames the file to include CPU architecture, either 'amd64'
  or 'x86'.
* Added --nosimcopy option to SCons 'run' targets to avoid automatically
  copying cross-built simulation firmware in openwsn-fw.
* Updated setup 'install' target to select and copy the proper simulation
  firmware variant from the linux/windows directories, up to the
  'sim_files' directory. Implemented with a custom 'build_py' class that
  extends the setuptools default when building the package data directory.
  Exclude the firmware variant directories from installation.
updating README.md
Merge pull request #64 from kb2ma/SW-130b

SW-130. Distribute simulation module variants, and select at install time
updating StackDefines.py after merging #51.
SW-133. Fixing calculation of drift. Module to record debugpins to VCD (WIP).
SW-80. Cleaned up.
SW-80. quantum activity for ISR and TASK. radio debugpin implementation..
SW-133b. Add debugging information for overflow duration.
SW-133. Fix per Tengfei's e-mail. SW-80. Extra debug pins.
SW-133. Fix scheduleIn function in BspBsp_timer.py
SW-133. Fix sheduleIn function in BspBsp_timer.py.
SW-133. Fixing implementation of BspTime for Python board.
SW-133. rename wireshark debug button.
SW-80. Adding button to enable GoLogic debug (WIP).
SW-80. Links to download pages. Remove unnecessary comments.