Merge pull request openwsn-berkeley#267 from openwsn-berkeley/develop…

…_FW-492

FW-492. SF0 implementation.

Merge pull request openwsn-berkeley#235 from openwsn-berkeley/develop…

…_FW-456

FW-456. Fixed.

Merge pull request openwsn-berkeley#208 from openwsn-berkeley/develop…

…_FW-421

FW-421. Fix.

Bumping version number of preparation of release.

Merge branch 'develop'

release 1.4 for OpenWSN

release tag 1.2.0

tagging the code for version 1.0.0. Fixes openwsn-berkeley#104.

creating a release tag for 1.0.0