software/slapos-testing: install rubygemsrecipe[test] extra

When invoking tests with setup.py test, missing eggs are installed before
running tests, using their latest available version, but we want to always
install eggs using buildout and using pinned versions.

software/slapos-testing/software.cfg

@@ -99,7 +99,7 @@ setup = ${slapos.rebootstrap-repository:location}
 
 [rubygemsrecipe-setup]
 <= setup-develop-egg
-egg = rubygemsrecipe
+egg = rubygemsrecipe[test]
 setup = ${rubygemsrecipe-repository:location}
 
 [eggs]
@@ -224,6 +224,7 @@ pycurl = 7.43.0.2
 pyflakes = 2.0.0
 zope.testing = 4.6.2
 urllib3 = 1.24.1
+pathlib = 1.0.1
 # Required by:
 # caucase
 PyJWT = 1.6.4