Merge: github_merge tool

Extraction of the github API in its own lib and rewrite of my nodejs script in pure Nit

Pull-Request: #409
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>

diff --cc tests/testfull.sh
index c53ce27,13df5e3..af97d0c
--- 1/tests/testfull.sh
--- 2/tests/testfull.sh
+++ b/tests/testfull.sh
@@@ -17,6 -17,5 +17,7 @@@ don
        ../src/test_*.nit \
        ../contrib/sort_downloads/src/sort_downloads.nit \
        ../contrib/pep8analysis/src/pep8analysis.nit \
+       ../contrib/github_merge.nit \
 -      ../contrib/github_search_for_jni/src/github_search_for_jni.nit
 +      ../contrib/github_search_for_jni/src/github_search_for_jni.nit \
 +      ../contrib/inkscape_tools/src/svg_to_png_and_nit.nit \
 +      ../contrib/inkscape_tools/src/svg_to_icons.nit