Fix critical crash when running on non utf-8 environment.

Review Request #7395 — Created June 8, 2015 and submitted — Latest diff uploaded




When running on non UTF-8 environment with mercurial as repository RBTools crashes for every command with message:
'CRITICAL: 'utf8' codec can't decode byte 0xb3 in position 22: invalid start byte.'. This is caused by assumption in execute method.

Now we are using sys.getfilesystemencoding() instead of assumpted 'utf-8'.

Running on non UTF-8 environment (Win7, x64 PL) does not cause error anymore.