Disable buttons unless form is dirty

[vinistock]

Partial implementation of #340.

Make submit buttons disabled and grayed out by default. When a value is changed in an input, the corresponding button becomes enabled and orange as was the previous style.

Saving a new value for a setting will also cause the button to become disabled and only a second change will then enable it again.

@denny let me know what you think.

[codecov[bot]]

Codecov Report

Merging #349 (37ba123) into master (5cdd160) will not change coverage. The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #349   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           62        62           
  Lines         1644      1646    +2     
=========================================
+ Hits          1644      1646    +2     

Impacted Files	Coverage Δ
spec/features/editing_settings_feature_spec.rb	100.00% <100.00%> (ø)

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[denny]

Ooh, nice :smile: Thanks!

I think you need to key into a different JavaScript event for the text inputs - they're not updating the button status until I leave the input, which means I can't click the submit button straight after typing a new value in. I think there's an 'input' event for text and textarea that triggers as soon as you type the first new character?

[vinistock]

Oh, nice! I didn't know about the input event before. It will now enable the button as soon as typing happens.