Add Force Sync option to repo plugin

[andrewgoktepe]

This adds a new checkbox option called "Force Sync" which will add the --force-sync option when running "repo sync".

[andrewgoktepe]

The Jenkins build failed at checkstyle. The first error is unrelated to my change. The second issue is complaining about the number of parameters in the constructor, which I'm not sure is a showstopper.

[jenkinsadmin]

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[rsandell]

Well we should avoid putting more options into the constructor. Better to add a

@DataBoundSetter
public void setForceSync(boolean forceSync)

[rsandell]

And if I run checkstyle on the master now, there are no checkstyle errors, so it does seem related to your change.