our goal is to make this as complicated as possible for the OP, here is my suggestion:
to achieve uniform output from all your leds, you need to run them in a strictly series chain, no parallel. since you only have 3.6v to work with from a battery, you'll need to step up your voltage to provide enough bias voltage to push the current through 4 (or more) leds.
the texas instruments tps61040 is an easy to use switching boost regulator that can be configured to operate in a constant current mode. you will need one of the ICs (easy to use sot23-5 package), a schottky diode, a small inductor and a few passives.
here's some info on the boost converter:
https://projects.dimension-x.net/archives/98
now since you're dealing with Lithium Ion batteries, you need a safe charger. I recommend the MAX1551 dual input Lion/Lipo charger. In an easy to use sot23-5 package, the 1551 offers both USB and dc wall adapter charging inputs. You can charge your wireless lightbar from your PC, or from a wall adapter. The 1551 requires no active external components, a few capacitors are recommended for decoupling input and output voltages.
More info on the 1551:
**broken link removed**