Prettifying the plantings page.

Added a couple of tiny methods on Crop, and delegated them across to
Planting, to easily display the default/first scientific name, and to
show the number of times a given crop's been planted.

Sadly, the tests randomly fail on my box saying "No route matches
{:controller=>"plantings", :action=>"show"}" which is just nonsense. I
have no idea why it's doing that, so I'm committing it anyway, in the
hopes that either someone can tell me what's up, or else it's just a
glitch on my dev box.
Minor tweaks to plantings page.

Tests still broken for me.  WTF is this even?
Merge branch 'dev' of https://github.com/Growstuff/growstuff into prettier-plantings
added 'where' to planting info (incl. location if known)
Fix one-argument calls to link_to.

Fixes broken tests.
Don't show () on plantings/show if no location given.

Can someone explain the semantics of nil and defined? to me?
add .collapse class to the header menu to fix the remaining mobile menu issues. See https://www.pivotaltracker.com/story/show/44352329
Stringify gardens as their names.
Simplified some code using Garden.to_s.
Test display of location on plantings/show.

As discussed at
https://github.com/pozorvlak/growstuff/commit/d87a1ee4fdd15153537382ddbfa16e3e3d9672a5.

The version of app/views/plantings/show.html.haml from commit 97ce623
fails the "()" test, as expected.
Merge pull request #118 from sabreuse/menu-collapse

Fix the remaining mobile menu issues
Merge pull request #117 from pozorvlak/prettier-plantings

Prettier plantings