Incompatibilities between protoc and protobuf_python version possible on install

[GoogleCodeExporter]

When installing pbandj the protoc version and protobuf_python egg version
must match to make sure the python _pb2 modules generated by protoc are
compatible with the protobuf_python implementation that is installed. 

Original issue reported on code.google.com by walker.z...@gmail.com on 29 Apr 2010 at 6:18

[GoogleCodeExporter]

Partial fix by requiring protobuf version to be the same as protoc version 
instead of
>= protoc version.  

Original comment by walker.z...@gmail.com on 30 Apr 2010 at 12:11