version: Make sure package.json is clean

In case we write the new version number and commit, we may be committing
changes in package.json that were not intended to be committed. That is
why the commit version step will proceed only if package.json is clean.

Change-Id: c66dc421bc
Story-Id: SF-23
release start: Fix formatting issues

Change-Id: 0128e92264
version: Roll back package.json on error

Change-Id: 64c4231801
wip

Change-Id: 06c9d9982e
Story-Id: SF-6
wip

Change-Id: 6be6e13ae0
Story-Id: SF-6
wip

Change-Id: f961f519a5
Story-Id: SF-6
wip

Change-Id: d3a353bf2c
Story-Id: SF-6
wip

Change-Id: 85fa888ed4
Story-Id: SF-6