[usecase-webapi][XWALK-2251] Improve nfc usecase

- Add clearLog function and setEnvironment function
- Removed redundant test functions
- Modified AddMessage function
- Improve test steps and excepted results
- Failure analysis: NFCManager::startPoll(), NFCTag::readNDEF(), NFCTag::writeNDEF(), NFCPeer::sendNDEF() function do not work

Impacted tests(approved): new 0, update 1, delete 0
Unit test platform: [Tizen IVI]
Unit test result summary: pass 0, fail 1, block 0