Role ordering is not stable

[jgustie]

Using 0.2.0-beta.3 the RBAC generator is modifying files on every pass. I think this is due to the #235 changes: the ultimate ordering of the policy rules slice is now determined by a map iteration.

I'm still transitioning from Java to Go, but I think the fix is to aggregate the rules keys into another slice, sort the ruleKey slice and iterate over that when building the list of policy rules.

[DirectXMan12]

they should be being sorted @haiyanmeng FYI

[DirectXMan12]

/kind bug

[haiyanmeng]

/assign @haiyanmeng