This try to swallow as much as possible slave instance bad requests.

I updated the dropbear url because it wasn't uploaded to network cache.
I kept an old version because :
 * our patches don't work anymore with the latest version.
 * the latest version (at the date of this commit, doesn't have an
   interesting changelog).
 * by laziness.

Boa is a single-tasking HTTP server. That means that unlike traditional
web servers, it does not fork for each incoming connection, nor does it
fork many copies of itself to handle multiple connections. It internally
multiplexes all of the ongoing HTTP connections, and forks only for CGI
programs (which must be separate processes). Preliminary tests show boa
is capable of handling several hundred hits per second on a 100 MHz
Pentium.

Description from : <http://packages.debian.org/squeeze/boa>
Building method inspired by :
<http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/www-servers/boa/boa-0.94.14_rc21.ebuild?view=markup>

Using a graceful restart :
<http://httpd.apache.org/docs/2.2/stopping.html#graceful>

This is usefull for slave_partition_list

ChangeLog entry :
* New features
  - Added Unix socket support (e.g. "connect = /var/run/stunnel/socket").
  - Added "verify = 4" mode to ignore CA chain and only verify peer certificate.
  - Removed the limit of 16 IP addresses for a single 'connect' option.
  - Removed the limit of 256 stunnel.conf sections in PTHREAD threading model.
    It is still not possible have more than 63 sections on WIN32 platform.
* Optimizations
  - Reduced per-connection memory usage.
  - Performed a major refactoring of internal data structures.  Extensive
    internal testing was performed, but some regression bugs are expected.
* Bugfixes
  - Fixed WIN32 compilation with Mingw32.
  - Fixed non-blocking API emulation layer in UCONTEXT threading model.
  - Fixed signal handling in UCONTEXT threading model.