Fix python3 str vs byte on Cygwin

As stated in http://stackoverflow.com/q/26537945, the output of
`ctypes.cdll.cygwin1.cygwin_conv_path` is always a byte string so
it doesn't work when checking it on cygwin against simple string
which is unicode string on python3
Convert input of `cygwin_conv_path` into bytes

Otherwise in python3, it will be converted into a simple `/`
Merge branch 'fix-python3' of https://github.com/zigarn/Pydev into zigarn-fix-python3
Fixed issue where we'd encode/decode when we shouldn't.
Merge remote-tracking branch 'origin/development' into development
Merge branch 'development' into new_preferences