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
Corrects ERR trap

function fw_exists was returning a non-zero code, which was always
triggering the ERR trap. This commit fixes that issue for the "go"
dependency - it still needs to be fixed for others.

This also updates the ERR trap to have access to the entire
bash function stack, which would be very useful for debugging
Apply ERR fix to all dependency installer files

Minor bugs fixed:
- Ruby was triggering ERR trap
- Erlang was untarring nonexistent file
- Composer was being installed into nonexistent directory
- Mono was incorrectly trying to move it's install location
- Yesod now depends on haskell
Fixes #914 - cloc is a prerequisite
Fixing obvious fw_depends errors in install.sh files
Adding missing dependencies
Fix ERR syntax for prerequisites
Fixing minor issues
Fixing dotfile backup in prerequisites install
Update php.sh
Merge pull request #900 from hamiltont/install_box

Compartmentalize install files

All the install scripts are working, but some tests may be broken.