fix Makefile chmod (644)
replace MD5SUM with HASH
add PKG_MIRROR_HASH when PKG_SOURCE_PROTO:=git

(PKG_SOURCE_PROTO:=svn tarballs are not reproducible for now)

Signed-off-by: Etienne Champetier <champetier.etienne@gmail.com>

Adds YAJL (Yet Another JSON Library), a C library for parsing JSON.
Includes patches for uClibc support.
Improved from version used internally at Who's On My WiFi since Feb 2014.
Adds myself as maintainer.

Signed-off-by: Charles Southerland <charlie@stuphlabs.com>