Merge pull request GoogleCloudPlatform#190 from dlorenc/update36

Update to Python 3.6.5.

Update Python interpreters to 3.5.5 and 3.6.4 (GoogleCloudPlatform#177)

Replace "Container Engine" by "Kubernetes Engine". (GoogleCloudPlatfo…

…rm#176)

Skip test_xmlrpc_net when building python interpreters (GoogleCloudPl…

…atform#175)

Skip test_xmlrpc_net when building python interpreters (GoogleCloudPl…

…atform#175)

Update system tests script (GoogleCloudPlatform#171)

Update system tests script (GoogleCloudPlatform#171)

Update system tests script (GoogleCloudPlatform#171)

Merge pull request GoogleCloudPlatform#170 from nkubala/environment_fix

return string instead of bool in integration test sample app env handler

Merge pull request GoogleCloudPlatform#155 from GoogleCloudPlatform/d…

…greiman/buildsh

Separate building and testing phases via --build and --test flags.