bumps version to 0.4.3
fix(tests): update karma plugins and do not run tests on start of 'grunt dev'

After updating to latest grunt-karma (fabs release 0.4.2), running test on startup produces an error. So we have to disable running tests on startup and run them only if files will change while 'grunt dev' is running.
fix(watch): increase watch interval to reduce cpu load
doc(changelog): update changelog for 0.4.3
Merge branch 'hotfix/0.4.3'