tests: forces consistent import syntax
BufferExt: rename to bufferutils
ECPubKey/ECKey: separate to two files
tests: use filepaths directly

After a long IRC discussion, it was decided that the use of direct
filepaths instead of the module is a more pure form of testing ,
although it may provide less overall coverage than the mixed integration
style imports used previously.

This will need to be remedied by further integration testing in
/test/integration.
Merge pull request #176 from dcousens/rename

Project structure cleanup