Add json-mode recipe

https://github.com/joshwnj/json-mode
Merge pull request #1084 from milkypostman/drew_adams_libraries

Add a collection of Wiki packages for Drew Adams.
Fix apropos-fn+var recipe.
add ac-c-headers
Remove helm-c-moccur.

Closes #1102
Merge pull request #1103 from zk-phi/ac-c-headers

add ac-c-headers
Merge pull request #1101 from yasuyk/json-mode

Add json-mode recipe
Removed files spec from recipe.
Merge pull request #1100 from gstamp/add-cucucmber-goto-step

Recipe for cucumber go to step.
"nrepl" is now called "cider"

See https://github.com/clojure-emacs/cider/issues/375
Show old names on package page, and include download counts for old names
And remove corresponding TODO
rename abl-mode to abl
Rename cg-mode to cg.
Rename emacs-highlight-unique-symbol to highlight-unique-symbol.
Rename emacs-toml to toml.
Rename helm-mercurial-queue helm-ls-hg.
Rename latest-clojars to latest-clojar-libraries.
Remove mark recipe. Added duplicate "show-marks" with new name.
Rename pretty-symbols-mode to pretty-symbols.