Move installation to bash

Logically this code is quite similar to before, it's just
using the shell directly instead of going through python.

This defines a trivial dependency system with `fw_depends`.
Where possible, I have specified inherent dependencies (e.g.
siena depends on play1), but callers should declare their
dependencies in proper order to be safe.

Bugs Fixed:
- HHVM: Was forcing trusty name on all Ubuntu versions
- WT: Was checking for installs/namak
- Ruby: Removed single quotes preventing proper source
- Ruby: Was attempting to use rvm before sourcing ~/.profile
Adding install.sh files based on benchmark_config files

Also removes accidentally added ._dart.sh
Added zeromq as dependency of mongrel2
Added comments on how to use static cache when developing
Declaring /bin/bash where appropriate
Error handling for installation
Ensure consistent ENV
Enable framework-specific install directories and environment

This commit is my proof-of concept, only the 'go' test works right now.
You can look at go/ to see the changes required on a per-framework
basis - essentially I've modified go/setup.py to move the declaration
of the environment into go/bash_profile.sh

Each framework now gets a personal <framework>/installs directory, and
can declare any needed environment variables in
<framework>/bash_profile.sh, such as modifications to the PATH.

The FwBm code now provides an FWROOT environment variable to
*all* shell scripts (instead of ~/Frameworks being assumed).
Also, an IROOT environment variable is provided to any framework-specific
files (e.g. install.sh and bash_profile.sh) for the location of the install directory
for that framework. See go/bash_profile.sh to see me using both IROOT and
FWROOT.

By using IROOT, the strategy for installation is still controlled by python code and
the frameworks just reference IROOT and FWROOT in their scripts. These
variables are a nice step towards solving #448

The new function replace_environ in setup_util.py goes a long way towards
addressing #899 - as you can see I've removed all the changes to the ~/.bash_profile
from prerequisites.sh (and this commit serves as proof that everything still works) and
most of the changes from config/benchmark_profile