Update github method declaration to use keyword args
Add test for github and emacsmirror install methods
Fix magithub recipe

Also make it depend on magit.
Allow custom format string for "el-get-github-default-url-type"
Support "user/repo" for pkgname in github recipes
Convert all github recipes to github type

This automated convertsion was done with the following sequence of
commands:

cd recipes
 # Replace :url with :pkgname "user/repo"
perl -iBAK -lape 's{^(\s*):url\s+".*github.com/([^/]+)/([^.]+)\.git"}{$1:pkgname "$2/$3"}' *.rcp
 # Change :type from git to github if recipe has a :pkgname property
for x in *.rcp; do if grep -q ":type.*git" $x && grep -q ":pkgname" $x; then perl -iBAK2 -lape 's/:type\s+git\b/:type github/g' $x; fi; done
 # Clean up backup files
rm -f *BAK *BAK2
cd ..

These commands may be repeated at any time in the future to convert
newly-added recipes.
Remove harmful use of "el-get-as-string"

It would convert nil to "nil", preventing error detection.
Test to make sure a broken recipe raises an error
Refactor github user/repo parsing into separate function
Add github-tar method
Add branch selection support to github-tar method
Add github-zip method
Use the standard ":pkgname" instead of ":reponame"
Support "user/repo" for pkgname in github-tar/zip recipes
Munge recipes befor handing off to stock tar/zip methods

In particular, http-tar needs ":url" and ":options" properties, and
http-zip needs ":url".
Add test for github archive methods
Use github method's user/repo parsing ing github archive methods
Merge pull request #559 from DarwinAwardWinner/github-archive-methods

Github archive methods
For :post-init single-funcall case, also allow macros and other callables
Fix check for callability

It no longer throws errors.