Map domain_name variable for use by coe

Add a variable mapping to expose the domain_name variable
to the coe::base class.

Change-Id: I4d45a4873792b21620dfc8dda965f373d1831319
Partial-Bug: #1277712
Merge "Map domain_name variable for use by coe"
Merge remote-tracking branch 'upstream/master' into coi-development