commit: Hide --disable-fsync option, add --fsync which takes a boolean

Per discussion on mailing list, the --disable-fsync has a
double-negative thing going on; --fsync=false is clearer.
core: Fix g_file_get_uri/get_parse_name for non-root ostree files
tests: Add a test which exercises --fsync=false
pull: Emit a better error if the remote isn't found

The generic GKeyFile error isn't quite informative enough here.

I hit this with the new compose process where we don't automatically
inject a configured remote into the generated disk images; we expect
people to add them.

https://bugzilla.gnome.org/show_bug.cgi?id=731346
docs: overview: Explicitly call out dpkg/rpm

To be more clear that we don't handle "inventory".
doc: Update links to Continuous
doc: No need to emphasize the poweroff vs other OSes so much
doc: adapting-existing: Update story on latest /usr/lib/passwd bits
doc: Update overview a bit

Link to docker, note in introductory paragraph the goal of package
composition on a server.
tests: Add a test for an empty /etc directory gaining content

https://bugzilla.gnome.org/show_bug.cgi?id=731924
libostree: Add ostree_repo_remote_add() API, port "ostree remote add"

At least one external tool is using the API, and wants to add a
remote, but all of the logic right now is in the tool.  Move it to the
library.

https://bugzilla.gnome.org/show_bug.cgi?id=731984
remote: Fix regression in previous commit wrt adding branches

branches is always NULL at that point, we want to look at argc.

https://bugzilla.gnome.org/show_bug.cgi?id=731984
remote: Minor argument parsing cleanup

Only access relevant portion of argv after we've verified argc.

https://bugzilla.gnome.org/show_bug.cgi?id=731984
packaging: BR e2p
[staticanalysis]: Fix two uses of uninitialized variables

https://bugzilla.gnome.org/show_bug.cgi?id=732020
[staticanalysis]: Add missing va_end()

https://bugzilla.gnome.org/show_bug.cgi?id=732020
[staticanalysis]: Add assertion to pacify analyzer

This condition can't actually be hit, let's hint that's the case.

https://bugzilla.gnome.org/show_bug.cgi?id=732020
[staticanalysis]: Actually check errors on splice() of objects

We were using unsigned size when we should have been using signed,
this means we basically weren't checking for errors on write...ouch.

Luckily if we e.g. hit ENOSPC during a pull, the checksums wouldn't
match and we'd return an error anyways.  However when writing an
object, we'd end up silently ignoring it =/

https://bugzilla.gnome.org/show_bug.cgi?id=732020
[staticanalysis]: Fix some dead code

One was an unused variable, the other is actually dead because we
can't have mfile != NULL.

https://bugzilla.gnome.org/show_bug.cgi?id=732020
[staticanalysis]: Fix in_status_line

We need to end the status line *after* we've done a pull, as ostree
admin upgrade does.  Also add the correct in_status_line assignment.

https://bugzilla.gnome.org/show_bug.cgi?id=732020