Basic planter statistics leading towards planter rating

[sebastiangaertner]

The planter list and planter info should have

• Total trees
• Approved trees
• Rejected trees
• Trees not yet verified
• any flags attached to the planter

This will help a lot and will be the start of a planter rating.

[nmcharlton]

This is largely a duplicate of Greenstand/treetracker-admin-client#132, although that issue only covers the stats on Planter Detail.
The main thing that's missing is the flags.