import js directory from jsrrdgraph for client side graph rendering

Source: https://github.com/manuelluis/jsrrdgraph@276b880
type: stick to the rrdgraph time specification

Reference: http://rrdtool.mirror.graemef.net/doc/rrdfetch.en.html#IAT_STYLE_TIME_SPECIFICATION
move width/heigth from plugins to type __construct
jsrrdgraph: RrdGraph.js: fix undefined 2nd argument of RrdVdef function

This fixes this error:
> TypeError: Cannot call method 'indexOf' of undefined at new RrdVdef
integrate jsrrdgraph in CGP
.htaccess: enable gzip on rrd files
add support for graphing I/O using the negative X-axis
jsrrdgraph: RrdGraph.js: gprint: fix check for undefined format in case of vdef

The GPRINT of a VDEF doesn't have a CF. For example:
> "GPRINT:avg:LAST:%5.1lf%s Last"
> "GPRINT:tot:%5.1lf%s Total\l"

The format will be passed via the cf variable, so format is not defined. But it
didn't show up in the legend. Firebug showed variable format isn't undefined,
but an empty string in case of VDEF. So just check for falsy.