[*] cleanup after the output of pbt check, setp 1; the pbt package.
cleanup after the output of pbt check, setp 2: the tests for the pbt package.
cleanup after the output of pbt check, setp 3.1: the setup plugin.
cleanup after the output of pbt check, setp 3.2: the install plugin.
cleanup after the output of pbt check, setp 3.3: the check plugin.
cleanup after the output of pbt check, setp 3.4: the new plugin.
[*] cleanup after the output of pbt check, step 3.5: the helloworld plugin.
[*] cleanup after the output of pbt check, setp 3.3.1: the check plugin returns.
[/|] Merge branch 'master' into cleanup
Merge pull request #58 from StyXman/cleanup

Cleanup
add pex resource
add requirements to project.pbt
clean up project.pbt a little
have the absolute path to the project in Project, add join_path utility function
install from project.pbt dependencies into deps
[/|] merge from master.