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
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
Merge pull request #200 from attlebish/plantingredirect

Redirect to Garden after deleting planting
Merge pull request #199 from Skud/cropwrangling

Make life easier for crop wranglers
Replace name validation with before_filter and add rake tast for empty names. Replace validation testing with before_filter tests.
Added validation for garden names.
fix up existing gardens with blank names.
Merge pull request #201 from IAMRYO/garden_name

Garden name
Merge pull request #193 from pozorvlak/replylink

Replylink