mdp-placeholder does not except interpolated values

[jrcollins4]

I am generating forms dynamically, and I am trying pass in an expression into the mdp-placeholder attribute:

<mdp-time-picker mdp-placeholder="{{input.label}}" ng-model="input.value"></mdp-time-picker>

This is not getting picked up and results in an empty placeholder.

[kilzid]

I created a PR #172 to allow interpolated values.

[therickwillis]

Running into this issue right now. Please approve this PR!

[VWoodin]

PR #177 addresses this issue. Please approve, seems like a couple folks are having problems with this issue.