download.sh OSX check fix

Checking for OSX works in OSX but not in Linux defaulting to Bash, looked at a few shell tricks, nasty.. went for alternative.

root@vagrant-precise-pangolin:/vagrant# echo $SHELL
/bin/bash

root@vagrant-precise-pangolin:/vagrant# curl -s -L rekon.basho.com | sh

Begining Install into 127.0.0.1:8098...
Downloading Rekon from Github

Download Completed
Extracting Source
Installing rekon to 127.0.0.1:8098...
Installed, now visit: http://127.0.0.1:8098/buckets/rekon/keys/go

Install Completed!
sh: 43: [: ==: unexpected operator

************************************************
Visit http://127.0.0.1:8098/buckets/rekon/keys/go in your browser
************************************************


Amended download.sh:43

if [ $OSTYPE == 'darwin10.0' ]; then

to

if [ `uname | grep Darwin` ]; then