IPaddr2: add local scripts about resource-agents

[dmuhamedagic]

I'm not exactly thrilled with this proposal, but it seems like there's no saying what can go awry with network equipment on IP address failover. @lge, what do you say?

[meteozond]

I see a bit different proposal for this feature.
If you are bringing up secondary interface with secondary address you will run into the problem of wrong response routing. In a regular situation it can be solved with post-up post-down options in your interface configuration.
Using resource agent for ip assignment prevents you from using such solution. Noted above options could be analogue of interface post-up post-down idioms, isn't it?

[b-a-t]

Agree with @meteozond - that's also a legit scenario. In general, it's better to have rarely used option, than not to have a necessary one. There are at least two use cases in which such a functionality is handy.