PSR-7 file upload parameter naming consistency.

[weierophinney]

• Is this related to quality assurance?
• Is this related to documentation?
  Upgrading my setup to released version of Lock file maintenance #70 caused some confusion. Updating parameter to help resolve it, and suggest a documentation edit to explain where the instances could come from, as I couldn't figure it out without looking at the diff changes of previous PR refactorings.

Add missing unit tests for new options.

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Originally posted by @alextech at zendframework/zend-filter#82

[weierophinney]

Thanks @froschdesign for review and catching same inconsistencies that tripped me up yesterday!
Do you have a a hint on why 5.6 php travis is failing? I did not modify anything travis environment related to @weierophinney work, so would think it should work continuing from his setup.

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Originally posted by @alextech at zendframework/zend-filter#82 (comment)

[weierophinney]

PSR-17, which is used via the package psr/http-factory, requires PHP 7. Mark those tests as requiring PHP 7 using @require PHP 7.

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Originally posted by @weierophinney at zendframework/zend-filter#82 (comment)

[weierophinney]

@alextech As it is now it introduces BC Break. We can avoid it by deprecating previous keys and adding new. Also we need to keep old setter/getter (marked as deprecated) and proxy to new one.

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Originally posted by @michalbundyra at zendframework/zend-filter#82 (comment)