feat(input): make expressions work for ng-Maxlength and ng-Minlength

[florianorben]

ng-minlength and ng-maxlength attributes do not accept expressions as
input parameter.
Make it work as intended. Fix based on #1077.

Closes #1405

[pkozlowski-opensource]

@florianorben did you synchronize your work on this topic with @witoldsz ? What is the difference between the 2 PRs? Is it based on comments from @mmikulicic?

@florianorben Florain, as you can see this can't be merged cleanly, could you rebase this on the latest master?

[florianorben]

@pkozlowski-opensource No I didn't, it's just basically his PR applied to a different problem.
Difference is: #1077 deals with min="" & max="" attributes on number-inputs, whereas this wants to fix ng-minlength & ng-maxlength on all inputs.
After your comment I realize it would probably make sense to include this PR in @witoldsz 's (or vice versa) -> less duplicate code...
@witoldsz - what do you think? - Afterall you came up with this solution.

Meanwhile I will rebase and check @mmikulicic 's comment

[lanterndev]

Just hit this bug, found this pull request, and noticed it looks stalled. Anything I can do to help?

[jbdeboer]

@florianorben I ran the tests against this PR and saw a few failures: http://ci.angularjs.org/job/angular.js-james/5/testReport/

Could you take a look and fix these failures? This PR didn't apply cleanly to the master branch; that may be the source of the bug.

[jbdeboer]

Closing this PR for now to keep the queue clean. Please re-open when the tests are passing.

[blowsie]

@florianorben your fix works fine for me, except its sets my fields as dirty