version up eggs. but pin pyOpenSSL to 0.13 for now.

pyOpenSSL requires cryptography and cffi, but cryptography tries to build cffi internally that may fail.
specify python executable explicitly for develop-eggs.
version up pyOpenSSL 0.14.

add custom build for cryptography and cffi eggs that are required by pyOpenSSL 0.14.
pyOpenSSL is no longer binary egg.
Check if sort and tail are correctly built.
Add python-cffi egg component.
Add python cryptography egg component.
Python openssl now depends on python cryptography.
Add findutils component.
Add rdiff backup statistics in the RSS feeds.
slapos-testing: Run tests for slapos.package also.
Merge branch 'erp5testnode-pyOpenSSL-0.14'

Conflicts:
	component/python-cffi/buildout.cfg
	component/python-cryptography/buildout.cfg
	component/python-openssl/buildout.cfg
slapos stack: fix installation of pyOpenSSL (Romain C.)