Ability to configure StochKit path in the app via  a conf script and a tool that will download and install StochKit2

The deployment of the app has been modified in the following way: 

1.) A new script stocks/conf/stochss-env.py , where users can edit their environment settings (STOCHKIT_HOME, AWS credentials) so that the app automatically becomes aware of those upon launching it with "launchapp". 

2.) Added a folder 'stochss/tools', which at the present contains the old install_linux.sh script (which the users should never execute, it is for configuration of VMs) and a new script that will automatically download the supported version of StochKit2, attempt to install it (along with dependencies) and modify the conf script in 1) to be aware of this new StochKit installation.