Add basic VWRAP support to SimianGrid. In practice this means a new LLSD login handler (need to figure out how to parse LLSD XML from PHP) and the following capabilities: agent_seed_capability, agent/info, agent/inventory, agent/inventory-skeleton, rez_avatar/place

Requires:

• A well tested and understood capability router and security model for capabilities
• rez_avatar/request support in the SimianGrid OpenSim connectors

See the resolution on #19 to see why this was marked as WontFix for now