Add some small utilities

[netsettler]

• In ff_utils:

  • Add is_bodyless predicate on http methods (verbs) to say if they want a data arg. (I needed this in two different places recently.)

• In env_base:

  • Add EnvBase.set_global_env_bucket to avoid setting os.environ['GLOBAL_ENV_BUCKET'] directly. (I want to tell people to use this and not to set the env variables directly for now.)

[coveralls]

Pull Request Test Coverage Report for Build 2874548745

• 25 of 25 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.09%) to 70.599%

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Totals
Change from base Build 2834185419:	0.09%
Covered Lines:	5290
Relevant Lines:	7493

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💛 - Coveralls