plugin/memory: add cache

Closes: https://github.com/pommi/CGP/issues/71
inc/html.inc.php: fix canvas graphs

Include graph.php instead of non-existing plugin/$plugin.php.
plugin/uptime: fix legend format (.1lf -> %.1lf)

Closes: #72
plugin/libvirt: show (v)CPU time in milliseconds
Add base option (1GB=1024Mo)
Add base on all df plugins
detail.php: fix canvas graphs

Include graph.php instead of non-existing plugin/$plugin.php.

Closes #75
plugin: fix typo in temperature type
graph.php: fix undefined index 'type' in $plugin_json[$type]

When type wasn't set in the plugin json, a "PHP Notice:  Undefined index"
would pop up. Just default to 'default' when type isn't set.

Closes #76 #77
plugin/tcpconns: fix missing port number in rrd title

Closes #78
Add support for multiple types db
Add LVM plugin
add percentile support to network traffic graphs

Set $CONFIG['percentile'] to a number and a XXth percentile line + legend
will be added to all network traffic (if_octets) graphs.

Closes #81
Merge remote-tracking branch 'feandil/for_upstream_lvm'
Merge remote-tracking branch 'dhchen/master'
type/base: replace array_merge by + sign to merge a fallback array

array_merge resets the index, while in case of $this->colors and
$this->legend, we'd like to keep the index. An irq plugin sample:
array(1 => 1, 'ERR' => 'ERR') must not become
array(0 => 1, 'ERR' => 'ERR') after an array_merge.
Keep the list of plugins sorted
Use config time_range for canvas graphs
Merge remote-tracking branch 'feandil/time_range'
rm plugin.php

Forgotten in commit:
v0.3-77-gbf56a64 [remove ajax js code]