Improve bundle validation.

[frankban]

Improve the validation logic by:

• simplifying error management and code flow;
• making each function only receive what strictly required;
• adding more strict type checks;
• adding service annotations validation;
• fixing some subtle bugs in unit placement when the unit is 0;
• separating internal validation functions into more reusable bits;
• changing the validation tests so that each test is executed separately, with a real bundle content;
• changing the validation tests so that only the public API is exercised.

Also simplify the validation public API: the validate function is the only exposed API now.

Also ensure there are no false positives when validating bundles by testing the validation logic against the currently ingested bundle in the charm store. This is done with a functional test requiring network access.

QA: make test make fcheck (this will take a minute).

My apologies for the long diff, but lots of code are tests and I didn't find an easy way to subdivide the work. Thanks a lot!

[mitechie]

:+1: No qa. Thanks for the update. Please note that we need to cut tihs work off. This much validation in python not as part of charmhelpers or as part of the juju store command in Go is something we need to limit. The goal is to allow the GUI to read/change/export bundles with placement and this work has gone quite a bit past that with this thorough validation of the format that will be changing and that we only support bundles from the charmstore which we know will be valid.

[jujugui]

Test FAILed. Refer to this link for build results (access rights to CI server needed): http://ci.jujugui.org:8080//job/juju-bundlelib/32/ Test FAILed.

[makyo]

:+1: thanks for all the reorganization and the ftests! QA ok

[frankban]

:shipit:

[jujugui]

Status: merge request accepted. Url: http://localhost:8080/job/juju-bundlelib-merge