os-github.el: Fixed some typos
os-github.el: support private repos.
os-github.el: support multibyte
os-github: use authentication data also for os-github-fetch-json-page

github only allows a quite limited number of unauthenticated json
queries, so retrieve everything using the supplied authentication.
os: use node-property elements in property drawers

org-mode commit b60445cf introduced node-property elements to store
the individual properties of property-drawer s.

define two new functions os-property-drawer-to-alist and
os-alist-to-property-drawer to provide a shallow extra layer for an
easy transition.

XXX cleaner to remove the alist middle step.
os: os-headline-to-buglist calls os-headline-to-bug on its descendants

os-headline-to-buglist's paremeter is the headline element which
contains all bugs directly as its child headlines. the first element
of its contents is the section part with property drawer and text, all
other children are the headlines corresponding to bugs.

i don't understand why it could have worked the way it was.
Update README to reflect the need for a more recent org-element.el
ignore *.elc
add provide for each backend
update README to say to use require insead of load.
add suggestions to improve the auth system
Merge remote-tracking branch 'github-elsatch/master'
Merge remote-tracking branch 'github-rworks/master'
Merge remote-tracking branch 'github-coroa/master'

Conflicts:
	os-github.el
use links whenever it's possible.
Replace prefix `os-' by `org-sync-' for functions and variables and rename `os-sync' to `org-sync'.
Rename `org-sync' (was `os-sync') to `org-sync-update' and `os' to `org-sync'.
improve formatting in comments by adding `' around functions and variables name.
consistent naming
start an ERT suite for os.el