Bump version to 5.3.1; Update ChangeLog.
lpar: make dots in configure.in consistent with other plugins
rrdcached, rrdtool plugins: Honor the "DataDir" setting.

This fixes a regression introduced in:
bfd3f06ef4996707036756371c5724ebf2748821

Github: #380
rrdcached, rrdtool plugins: Add directory separator after datadir.

D'oh! Thanks to @rcpoison for pointing this out!

Github: #380
aquaero: Include aquaero plugin in config files.

Adds the aquaero plugin into the build system.
aquaero: New Aquaero sensors plugin

This plugin adds support for the Aquaero 5 sensors.
csv plugin: fix forgotten "datadir" in re-implement value_list_to_filename()

In the commit 7f90e30 the re-implementation of value_list_to_filename
forgot to prepend the datadir string.

Signed-off-by: Florian Forster <octo@collectd.org>
csv plugin: set datadir null when free

If you define twice DataDir:

    <Plugin csv>
	DataDir "/opt/collectd/var/lib/collectd/csv"
	DataDir stdout
    </Plugin>

the second time datadir will not be null and
you will get garbage in value_list_to_filename

Signed-off-by: Florian Forster <octo@collectd.org>
memcached plugin: actually connect when using a unix socket

Signed-off-by: Florian Forster <octo@collectd.org>
disable fields not available in varnish 2.0.x

Several fields were added in commit 8775392. 3 of them make the build
fail when varnish 2.0.x is used. This patch makes them available only
when using varnish 3.x.

The commit message of 8775392 gives more detail on the rationale behind
this way of doing.
curl_json plugin: support arrays

Allow access to data in JSON arrays.  For example

    { workers: [ { requests: 10 }, { requests: 10 } ] }

can all be accessed with

    workers/*/requests

or just one by using the index.

    workers/1/requests
curl_json plugin: document being able to access arrays
curl_json plugin: separate the cj_curl_perform in to the curl and yajl parts
curl_json plugin: support getting json from a Unix socket as well as a URL
curl_json plugin: use sstrerr for thread safety
curl_json plugin: style cleanups
curl_json plugin: free the socket name
curl_json plugin: document the new Sock option
curl_json plugin: add an example of array access to the documented uWSGI example
RedHat RPM spec: support for RHEL5

plus some minor updates: bump version to 5.3.1 & add usage example.