Stackdriver Integration version detection too strict

[chingor13]

with an app.yaml containing enable_stackdriver_integration: true, we do not allow a wildcard version for google/cloud, google/cloud-logging, or google/cloud-error-reporting.

Additionally, if a composer.lock file is present, we should respect the locked version when doing our version comparison.

[tmatsuo]

Yeah. Right now, it fails all the constraints without the lower bound.

[chingor13]

We can defer the version verification until the container build process after composer has run. Rather than just locating the stackdriver prepend file using the user's dependencies, we can do the version check at that time as well. It will take slightly longer to fail (composer will have run), but it will solve the dependency resolution issues. WDYT?