gem: explicitely set --no-format-executable

Gem, unlike Debian, sets it by default to ON (it seems). This has the
very unfortunate effect that one cannot guess how the bin scripts
are going to be called ...
release 1.9.7.rc4
fix mixup in ruby version detection

We now use ruby_executable everywhere the full path to the ruby
executable is needed instead of accessing raw values.
define lsb_release for opensuse
another fix for ruby version detection
Merge github.com:doudou/autoproj
arch: add the --needed option on install to avoid reinstalling up-to-date packages
osdeps.rb: remove double entry PacmanManager
ShellScriptManager: add support for execution as user

Some package managers (for example homebrew) do not need sudo rights to install new packages
add package manager homebrew (OS X)
use homebrew as default package manager on OS X
gem: make sure that default options are actually the default options

Distributions like arch and opensuse override the gem defaults in
their /etc/gemrc, breaking the expected behaviour under autoproj.

Make the default options explicit, and add a variable to allow
the user to configure it if he so chooses.
don't refer to manjaro explicitly, it should be resolvable as arch
osdeps: display which OS has been detected to the user
need to define Autobuild.progress and .progress_done in bootstrap
use File::PATH_SEPARATOR when applicable
remove Autoproj.find_in_path

Autobuild now has a version of it, and it was unused in the
autoproj codebase
osdeps: use primarily /etc/os-release to autodetect the OS
osdeps: fix nonsensical and non-portable test for lsb_release
install rubygems-integration on ubuntu as well

Note that 12.04 does not have it, so add a special case for this
version