Use istanbul for coverage reports, coveralls badge

Change-Id: I5704641578ef03908156df01cd017659160c2d00
coveralls config

Change-Id: I24daf032a1eb7fe66d7b0e7af260e8215a7336fe
branch is coveralls badge

Change-Id: I60221fcdf4dd3b393e79724ac0b99beeed1863c6
Finally, coverall works

Change-Id: I045c8b7ce3e14b94236b37efa7ea9e586b92de0f
Support coveralls, use istanbul for coverage reports.
Version bump

Change-Id: I98480806542493a625b970ea30d50f944a6e91bb
Merge branch 'release/v0.0.6' into develop