The NPM package installation had issues.

TL;DR

This updates the readme with detailed solutions on installing
as root with proper ruby support, and also updates the way
the bundler post-install script is run, mainly, making
it more user friendly.

Main Issues

1. When Bundler did not exist, a Ruby exception is logged.

However, the package still installs, and will log:

```
WARNING!

Bundle command(s) failed!

Continuing install, however Ruby support may not work.
```

Possible errors:

```
  bin/bundle-rb-gems: line 5: bundle: command not found
```

or

```
/Users/brent/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/rubygems/dependency.rb:298:in
`to_specs': Could not find 'bundler' (>= 0) among 15 total gem(s)
(Gem::LoadError)
  from
  ......
```

2. When installing as root (conventional for global NPM package).

Even if Bundler is installed as root too, it hangs when
called by the nobody user, so you may get hung up on Bundler
asking for the sudo password for not your user.

This may be inconsistent, though. Example: you may only
have to bypass this issue one time, and then it seems to work.