More versatile functionality

[timiwahalahti]

Hi,

I love this CMB2 field type and it's used in my many projects. Therefore i wanted to give some help with developing this further. This pull request adds and fixes following functionality:

• added possibility to save address, used same way as split_values setting ( Feature suggestion - possibility to save location data instead of just lat / lon #22, Address not saved on post saving #36 )
• added multiple filters to enable possibility for change default values ( Setting the starting point #39, Set default map location #24 )
• fixed behavior when used in repeatable group
• added unique id's for each field ( Bug: same ID for lat/long input fields #34 )

What i'm planning to do in near future:

• fix behavior when used as a single repeatable field