Add potion effects to bosses when they spawn.

With this feature you can add potions to the bosses when they spawn,
adding the ability to add strength to the boss for the first 30 seconds
making it harder for the first few seconds and once the effect wears
goes away the boss becomes easier. The syntax is in the same style as
potion items, except it uses either the potion effect enum name or the
potion effect id.

POTION_EFFECT:duration in seconds:amplifer

SLOW:360:4;INVISIBILITY:36000:0

If no duration is given, the plugin will default to sixty seconds. If
the amplifer was not provided, the plugin will default to zero. The
potion effect amplifcation starts at 0 being level 1.
If no duration provided, potion effects on bosses will last forever.
Swap amplifier and duration parameters in effect parser.

This changes the format from:

  <effect>:<duration>:<amplifier>

to a (pressumably) more user-friendly format of:

  <effect>:<amplifier>:<duration>

The reason for this swap is that the duration is more likely to be
wanted left at default than the amplifier. From previous user input
on the matter, it sounds like users generally want the bosses to have
"permanent" or "infinite duration" effects, and this change makes it
a little easier on them, not having to specify a duration.
Allow for lower case potion effect names.
Make numeric regexes require at least one number to match.
Allow for spaces between comma-separated potion effects.
Merge branch 'graywolf336-bleeding' into bleeding