DataSync tizen plugin implementation

SPEC=https://developer.tizen.org/dev-guide/2.2.1/org.tizen.web.device.apireference/tizen/datasync.html

BUG=XWALK-1061

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Running TCT:
 - install rpms on device:
     - libwbxml2,
     - sync-agent,
     - oma-ds-agent (and start: systemctl start oma-ds-agent.service),
 - copy 'tct-datasync-tizen-tests.wgt' to device,
 - install and run application,

Current TCT datasync passrate: 63/63

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This is class for marking exception/error in code. It is used in ResultsOrException to return from function result or exception (could rename it to error for example if thats better).

Google style guide diallows exceptions. There is no single throw|catch in my code so I mean that C++ exception handling is not used in this code. Probably this should compile with -fno-exceptions.