[6.0][mediacontroller] add playback action enum, listeners to server pbInfo and chang...

[6.0][mediacontroller] add playback action enum, listeners to server pbInfo and change iconURI

[acr]
http://suprem.sec.samsung.net/jira/browse/TWDAPI-245

[description]
>> refactor_02 <<
+ change iconURI to NOT readonly
+ add listeners in serverPlaybackInfo
+ add playbackAction enum
+ add onplaybackactionrequest

[verification]
tested manually in chrome console
tct-mediacontroller-tizen-tests fails with 2 TC:
- MediaControllerServer_iconURI_attribute.html <- has to be modified,
  because attribute iconURI is no longer readonly
- MediaControllerServerInfo_iconURI_attribute.html <- has to be modified,
  because attribute iconURI is no longer readonly

Change-Id: I1a234adbab71be72ec6c24a7fec4e8b5d7fcc55c
Signed-off-by: Dawid Juszczak <d.juszczak@samsung.com>