Add template, label & input classes, and placeholder options

[todda00]

PR to add some additional autoform options:

Usage

In the #afModal you can add the following options:

template

Can use any template string that autoform accepts. For example:

template='bootstrap3-horizontal'

labelClass

Defines a bootstrap class for use when the horizontal class is used, how many columns should the label take? For example:

labelClass='col-sm-3'

inputColClass

Defines a bootstrap class for use when the horizontal class is used, how many columns should the input take? For example:

inputColClass='col-sm-9'

placeholder

Set to true if you wish to use the schema label for the input placeholder.

placeholder=true

[todda00]

Might remove the placeholder option, as the only way to remove the normal label would be to remove it for all elements, then there would not be any label for non text field inputs.

[mpowaga]

@todda00 Many thanks for this PR and sorry for late response.