[form-field] inconsistencies now that select is supported

[willshowell]

Bug, feature request, or proposal:

Bug

Current Behavior

1. getMdFormFieldMissingControlError needs an updated message to reflect support for multiple types of controls

https://github.com/angular/material2/blob/3571f68a2de0833ee4741af8a0eb24d1da174f38/src/lib/form-field/form-field-errors.ts#L19-L23

2. ~MdFormFieldModule is re-exported by MdInputModule but not by MdSelectModule. (tracking https://github.com/angular/material2/pull/7263)~

https://github.com/angular/material2/blob/3571f68a2de0833ee4741af8a0eb24d1da174f38/src/lib/input/input-module.ts#L27-L33

https://github.com/angular/material2/blob/3571f68a2de0833ee4741af8a0eb24d1da174f38/src/lib/select/select-module.ts#L23

cc @mmalerba

[ghd8]

fyi - second point was already corrected in #7263

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