Add short date/time output formats to the Regional section in Admin Console

Currently each In-Portal language has a bunch of formats used to input/output date and time when user is viewing website on that language.

However we are surely missing following formats:

• short date output format (usually without year), e.g. "m/d"
• short time output format (usually without seconds), e.g. "h:i a"

By default these formats won't be used, but developer can start using them any time, when there is a need with following tag:

<inp2:unit-config-prefix_Field name="DateField" format="_regional_ShortDateFormat"/>
<inp2:unit-config-prefix_Field name="TimeField" format="_regional_ShortTimeFormat"/>