Handle new 'MIXED' stream domain

This commit adds an option to select the language for a stream, in
the case where it is ambiguous (committing to a MIXED stream).
Add basic configuration validation UI
Exclude intellij files from git
Fix AJAX URLs so that they work regardless of where the host is
Add basic check
Update to v6 web services.

This allows us to check the version of CIM when running the pre-build
check.
s/ANY/ALL/
Run check before each build, and check each node.
Formatting
Handle pre-fresno and fresno+ analysis in separate code paths.
Formatting
Add comments
Change AJAX request path
Make AJAX URLs relative.

This makes the config page work with different context paths, as
well as hostnames that might not match the one set in the global
jenkins configuration.
Fix typo
Skip updating checkers if more than one language was analyzed
Don't fail the build if analysis and defect checking are both disabled.

Now, if the user disables build/analysis/commit, and also disables
checking for defects after the build, the build will complete
without error. Previously, if no snapshots were found, the build
would always fail.
Call cov-build for C# analysis if version >= fresno
Don't worry about C# assemblies when using fresno analysis
Add documentation for general configuration