ASM-1322 Brocade 5424 IOM support added to Dell 8|4 puppet module

This commit checks that the switch is set to Access Gateway Mode before executing discovery. Fact discovery fails with a nonzero exit code if switch is not in AG mode.
Merge pull request #4 from dmohanty09/5424

ASM-1322 Brocade 5424 IOM support added to Dell 8|4 puppet module