IDEA-98030 Encoding problem in comments in hg4idea plugin in IDEA

Fix for http://youtrack.jetbrains.com/issue/IDEA-98030
The default encoding for Windows may be changed depending on the locale.
For example, Japanese is cp932.
And, if the HGENCODING is set to overrides the system default.

Please reference the following for the code page of Windows.
http://msdn.microsoft.com/en-us/library/2x8et5ee.aspx