Pgrok

- FEATURE: pgrok can now update itself automatically

- BUGFIX: Fix an issue where pgrok could never save/load the authtoken file on linux
- BUGFIX: Fix an issue where pgrok wouldn't emit log messages while loading authtokens

- FEATURE: -hostname switch on client allows you to run tunnels over custom domains (requires you CNAME your DNS)
- IMPROVEMENT: pgrok client UI now shows the client IP address for a request
- IMPROVEMENT: pgrok client UI now shows how long ago a request was made (uservoice request 4127487)
- IMPROVEMENT: pgrokd now uses and LRU cache for tunnel affinity data
- IMPROVEMENT: pgrokd can now save and restore its tunnel affinity cache to a file to preserve across restarts

- IMPROVEMENT: Improved developer documentation
- IMPROVEMENT: Simplified build process with custom version of go-bindata that compiles assets into binary releases
- BUGFIX: GitHub issue 4: Raw/Binary requests bodies are no longer truncated at 8192 bytes.