Add documentation from original CVS repo. Put one important change to the CHANGELOG top.

userguide.html from http://jpype.cvs.sourceforge.net/viewvc/jpype/jpype/site/doc/user-guide/userguide.html?revision=1.11
Convert userguide from html to rst.
Remove (old) JPype version string from userguide.
Merge pull request #56 from baztian/documentation

Documentation (userguide)