Create media element just once using inheritance chain

Change-Id: Idca7de1f3511a0c3f364f5c6bb9deac07281b383
Initialize UriEndPoint parameters in class contructor, not in children classes

Change-Id: Id5614604862c0b6e57441105838dc94f567a5d06
UriEndPoint: Remove magic numbers

Change-Id: I59f871aaf30852be25aa172a45d6da4ece4b7e8f
Remove unneeded include statements

Change-Id: Ie8ad7e5fc6a75ae8454974d5064c81c81c446937