Support for ME Identity Check Procedure (S13 and S13' interfaces operation)

[mnowa]

Add support for Mobile Equipment Identity Check Procedure consisting of ME-Identity-Check-Request (ECR) and ME-Identity-Check-Answer (ECA) diameter messages use by S13 (between MME and EIR) and S13’ (SGSN and EIR) reference points.
Both S13 and S13’ interfaces use same application id 16777252. The diameter command code is 324
For more information refer to chapter 6 of 3GPP TS 29.272