BaseTools ConvertMasmToNasm: Fix running script outside of a git tree
    
    The script previously would hit an exception if it was run outside of
    a git tree.
    
    The exception looked like:
    
    edk2/BaseTools/Scripts/ConvertMasmToNasm.py Version 0.01
    Traceback (most recent call last):
      File "edk2/BaseTools/Scripts/ConvertMasmToNasm.py", line 986, in <module>
        ConvertAsmApp()
      File "edk2/BaseTools/Scripts/ConvertMasmToNasm.py", line 984, in __init__
        ConvertAsmFile(src, dst, self)
      File "edk2/BaseTools/Scripts/ConvertMasmToNasm.py", line 209, in __init__
        CommonUtils.__init__(self, clone)
      File "edk2/BaseTools/Scripts/ConvertMasmToNasm.py", line 69, in __init__
        self.gitemail = clone.gitemail
    AttributeError: ConvertAsmApp instance has no attribute 'gitemail'
    
    Fixes: https://github.com/tianocore/edk2/issues/63
    Contributed-under: TianoCore Contribution Agreement 1.0
    Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
    Cc: Yonghong Zhu <yonghong.zhu@intel.com>
    Cc: Liming Gao <liming.gao@intel.com>
    Cc: Michael Kinney <michael.d.kinney@intel.com>
    Reviewed-by: Liming Gao <liming.gao@intel.com>