Parameterize Invocations per Minute limit

[jonpspri]

On faster Travis machines, the System Test fails because it runs into the Invoker's Invocations Per Minute limit. While this is a Good Thing in general, it's quite frustrating during a system test. This PR adds parameterization of the Invocations Per Minute limit to the test scripts so that the system test can raise that limit and avoid spurious failures.

Description

Related issue and scope

• I opened an issue to propose and discuss this change (#????)

My changes affect the following components

• API
• Controller
• Message Bus (e.g., Kafka)
• Loadbalancer
• Invoker
• Intrinsic actions (e.g., sequences, conductors)
• Data stores (e.g., CouchDB)
• Tests
• Deployment
• CLI
• General tooling
• Documentation

Types of changes

• Bug fix (generally a non-breaking change which closes an issue).
• Enhancement or new feature (adds new functionality).
• Breaking change (a bug fix or enhancement which changes existing behavior).

Checklist:

• I signed an Apache CLA.
• I reviewed the style guides and followed the recommendations (Travis CI will check :).
• I added tests to cover my changes.
• My changes require further changes to the documentation.
• I updated the documentation where necessary.

[tysonnorris]

The current default is 60 - won't setting this to 240 cause any tests that might rely on 60 to fail?
When does travis run on 'faster' machines? Is there an example failure at https://travis-ci.org/apache/incubator-openwhisk/?

[tysonnorris]

is invoker_use_runc required here?

[rabbah]

i dont see why runc should be in here either.

[rabbah]

Thanks @tysonnorris for reviewing this.
@jonpspri is there a particular suite that fails? There is a throttle settling pattern we've used inter-suite and intra-suite. Generally I'm OK bumping this limit in paramaterized way although there are actually throttle tests that depend on these limits.