Remove the numberOfVendors() function and supporting data structures.

Prior to this commit the numberOfVendors function was making a second
copy of store data. This copy was used to define the map markers on
the Map.js page. This commit connects the logic defining map markers
directly to the vendor store such that we no longer need to maintain
the extra structures used to implement numberOfVendors().

Conflicts:
	app/controller/List.js
Merge pull request #9 from osu-cass/bugfix-4059-first-search-fails-cherry-picked

Remove the numberOfVendors() function and supporting data structures.
Add static map image

I was able to add a static map image to the vendor detail page, but ran in
to some problems with the back button and reseting the src for the static
map image.
Fix back button problems and map loading

I was able to fix the back button problems, by refering to the correct
screen element in the on back cmd. I was also able to solve the map
loading problem, because it seems that I only loaded the map when a user
navigated from the list page to the detail page, and forgot to reset the
map when the detail page was navigated to by the productsdetail page.
Move staticmap variable initialization to the launch() function

Prior to this commit, the WhatsFresh static map controller variable
was initialized in the init() function, before the page resources were
available. This commit moves that line of code to the launch()
function, the normal place for initializing controller variables.
Consolidate static map building logic into helper function

Prior to this commit, the static map was declared in two separate
functions with copy/pasted code. This commit consolidates the
replicated code into a single, testable helper function called
'buildStaticMap'.