docs(guide/introduction): remove ambiguous "code-behind" jargon

This commit tries to remove the jargon and explain in plain English what
it means to add "code-behind" via a directive.

Closes #9684
docs(tutorial/step-7) - correct a url

Closes #9688
docs(tutorial/step-11): remove excess words

Closes #9690
fix(ngMock): $httpBackend should match data containing Date objects correctly

If a response or expectation contained a date object then `$httpBackend.expect`
was not matching correctly.

This commit encodes then decodes the object being matched to ensure consistency.

Closes #5127
docs(ngModel.NgModelController): remove extra 'to'

Closes #9702
fix(inputs): improve "input" event emulation for legacy browsers

Fix "tabbing through input sets dirty" and "update after blur"
bugs. Prevent special keys, like tab, from triggering model
updates. Update $sniffer event test so legacy Opera can use
native "input" event (thus avoiding keypress bugs).

Closes #1206
Closes #9623