Adds method for sorting products sold alphabetically

Products sold on market details page were not sorted alphabetically.
This commit sorts them alphabetically.
Fixes missing integration test

Test was set to pending because it was failing. The problem was the
presence of commas. These have been removed.
Adds method to sort payment methods alphabetically

Sorts payment methods alphabetically and adds conditional code that
checks for presence of "sorted" methods.
Fixes integration test

Integregation test was failing because payment methods were not
alphabetized. This has been corrected.
Moves sorting to view, amends test case

Addresses issues in
https://github.com/codeforamerica/human_services_finder/pull/94#issuecom
ment-18515654
Removes residual references to sorted methods

sorted_payments_accepted and sorted_products_sold no longer exist, so
the references to them have been removed.
Merge pull request #94 from codeforamerica/alphabetize_products

Alphabetize products