Production push: search nearby by distance, connect to twitter and flickr, etc

* Search nearby members: specify distance and units (km/miles)
* Connect member profile to Twitter and Flickr
* Added planting counts to crops pages
* Post comment page now shows all previous comments
* Added direct "reply" link to notifications
* Small fix to signup confirmation email formatting
* Added contact page (link in footer)
* Misc security tweaks and administrivia