Added a reply link to the notifications/show page

- sets subject "Re: whatever" for PMs
- also removed "sender=N" from PM link (wtf! -- it wasn't doing anything
    but it looked bad.)
removed unused random crop code
Added reply link to notification email.

Note: this breaks DRY but we couldn't figure out how to put it in a
helper and make it useable by both the controller and the mailer.
Suggestions/help much appreciated!
fixed failing notifications tests

(our non-DRY code, which we just pasted into the mailer, was breaking
this in a roundabout way. this is a quick and not very nice fix. The
whole problem is resolved by @pozorvlak's recent "no subject" fix for
notifications, anyway.)
Delete unused helpers.
Move reply_link into a helper.

 - keep @reply_link as an instance var, for testability
 - always use fully-qualified URLs, to reduce code duplication
Added crop wrangling hints to crops form.
added validation for en_wikipedia_url
moved member post feed to HAML
Factor out flickr controller code, for easier stubbing.
Test for photo thumbnails; stub Flickr username/id.
Removed obsolete test from views/photos/edit

We should consider just deleting this action entirely.
"auth" helper method in Member
Delete @flickr_login var in photos controller.

We didn't need any data from it that couldn't be got from @flickr_auth,
and eliminating it makes login_to_flickr less side-effecting and easier
to move around.
Move flickr code into Member model.
Add validation for name in garden model with test.
make it easier to wrangle scientific names
Merge branch 'dev' of https://github.com/Growstuff/growstuff into dev
Redirect to Garden after deleting planting
Save photos.