Add left indent to Views dependant options

When configuring a view field, you may have dependant options. For example in the "display settings", when overriding the HTML element for the field, you can specify a custom CSS class.
This checkbox is a dependant option and should be left indented. It has a class that allow easy targeting: .dependent-options.

By default, the Views module use a left padding of 15 pixels, but this is overriden by the MaPS Admin theme styles.