OS-479, DHCP service workflow fixes

    * dhcp_members was asigned but infoblox services wasnt restarted
    * dns server wasnt assigned in infoblox DHCP service
Merge pull request #13 from Vegasq/OS-479

OS-479, DHCP service workflow fixes
OS-500/422 Update EA values

OS-422 did not include the EA change in OS-500 which resulted in OS-500
reappearing.

Change-Id: I6344a95940d820fa2268d5510a44984d84e56ee1
OS-505, restart infoblox services after create/update/delete subnet
OS-549, unused exceptions removed, code refactored
Legacy code bug fixes
Merge pull request #23 from Vegasq/dhcrelay_agent_fixes

Legacy code fixes
Merge pull request #15 from Vegasq/OS-505

OS-505, restart infoblox services after create/update/delete subnet
Merge pull request #27 from roman-verchikov/OS-500/422

OS-500/422 Update EA values
OS-509, retry 3 times create IOS object, before fall with exception
Merge pull request #24 from Vegasq/OS-549

OS-549, unused exceptions removed
Merge pull request #22 from Vegasq/OS-509

OS-509, retry 3 times create IOS object, before fall with exception
OS-432 Update existing NIOS network on subnet create
Fixes after merge pep8 errors
Merge pull request #30 from Vegasq/pep8_fixes

Fixes after merge pep8 errors
Merge pull request #28 from Vegasq/OS-432_2

OS-432 Update existing NIOS network on subnet create
OS-295, get_subnet replaced with own implementation
OS-507 revert Arecord and PTRrecurd in exceptions cases
OS-553 remove namespaces during dhcp_agent disabling
Merge pull request #31 from Vegasq/OS-295_juno2

OS-295, get_subnet replaced with own implementation