Add method for user's to 'report offers' with decentralized banlist offchain + hide/show reported items

[dwasyluk]

Provide a way for users to report wasted offers like the ones shown above. Reports would be sent to the Syscoin team. If an item is blacklisted by the team due to reports from users it will not show up in the browse view unless the 'hide blacklisted items' filter is turned off. The blacklist should be driven by an offchain data source. The banlist should be configurable. The banlist should follow a spec so anyone can create their own list.

[dwasyluk]

To do this we'd rate-limit and secure-via-syscoin-auth an endpoint which allows reporting of items. The reports would include info on date, reporter-address, reporter-ip, guid being reported, reason for reporting. Reasons for reporting would be a series of pre-populated responses - we can source a good set of prepopulated responses for this type of thing from various other online marketplaces.

As a seperate deliverable we can develop a frontend interface for viewing the reports grouped by guid and through that interface have the ability to modify the overall ban list with a simple click to add additional banned items as reported by the community.

[dwasyluk]

Initial support for this is already in the current build, items needed to complete the implementation:

• styling of the report offer dialog
• update the offchain-proxy so that it has the endpoint needed to accept reports