pgmemcache: correct free function for memcached_stat_get_value

libmemcached 1.0.16 and greater switched to using malloc for
values returned from memcached_stat_get_value.
Merge branch 'master' of git://github.com/melor/pgmemcache

* 'master' of git://github.com/melor/pgmemcache:
  pgmemcache: correct free function for memcached_stat_get_value
Use pg_regress for make installcheck testing

This uses pg_regress to start a memcached instance, run test queries
from test.sql, and stops the memcached again. Needs root.

apt.postgresql.org uses this for integration testing for the Debian
packages; these tests discovered the incompatibility with libmemcached
1.0.16.
debian: new packaging to replace yada [#21]
Merge pull request #24 from ChristophBerg/regressiontests

Use pg_regress for make installcheck testing
Merge pull request #25 from saaros/debian

debian: new packaging to replace yada [#21]
Update NEWS and README a bit
debian: make sure the right pg version's binaries are in path
pgmemcache: stop using postgresql memory allocation in libmemcached

Libmemcached (and different versions of it) may or may not use the memory
allocation functions given to it with memcached_set_memory_allocators which
causes segmentation faults when calls to postgresql malloc/free are mixed
with calls to libc malloc/free.

It turns out that libmemcached calls from pgmemcache doesn't really need to
use postgresql's memory allocation functions as we never pass the data as-is
back to pg anyway, and we can just manually free the couple of temporary
allocations that are created.
pgmemcache: reorganize and clean up source code a bit

* Moved static function declarations to pgmemcache.c
* Fixed some minor indentation issues
* Fold do_memcache_set_cmd into memcache_set_cmd
tests: run memcached as a normal user so root access is not required
interval_to_time_t: handle span->day
Remove old servers from context when updating default_servers

libmemcached does not have a function for removing servers from the current
context so we must recreate the context from scratch when the list of
default servers changes.

The new functionality also makes it possible to implement a
memcache_server_delete() function at some point as requested in [#4] but
it's not implemented in this commit.
Merge pull request #26 from saaros/server-set-reset-context

Memory allocation and server list fixes
Add DEAD_TIMEOUT to supported behaviors
Merge pull request #27 from melor/behaviors

Add DEAD_TIMEOUT to supported behaviors
Make DEAD_TIMEOUT conditional on libmemcached >= 1.0.3

Reported by Patryk Kordylewski.
pgmemcache: release version 2.2.0