Modified descriptions on the bundler utilities

Modified descriptions on the bundler utilities that allow extra options to clarify that they are expected to be added after the command name.

Right now the description of a command is provided like:

``` shell
› bundle help gem
Usage:
  bundle gem GEM

Options:
  -b, [--bin=Generate a binary for your library.]
  -t, [--test=Generate a test directory for your library: 'rspec' is the default, but 'minitest' is also supported.]
  -e, [--edit=/path/to/your/editor]                                                                                   # Open generated gemspec in the specified editor (defaults to $EDITOR or $BUNDLER_EDITOR)
      [--no-color=Disable colorization in output]
  -V, [--verbose=Enable verbose output mode]
  -r, [--retry=Specify the number of times you wish to attempt network commands]

```

With no indication of where the options should be applied (before or after the command name). Its use is not interchangeable, generating errors like this:

``` shell
› bundle gem -t my-gem
ERROR: "bundle gem" was called with no arguments
Usage: "bundle gem GEM"
````
when the proper use is:

```shell
› bundle gem my-gem -t
      create  my-gem/Gemfile
      create  my-gem/Rakefile
      create  my-gem/LICENSE.txt
      create  my-gem/README.md
      create  my-gem/.gitignore
      create  my-gem/my-gem.gemspec
      create  my-gem/lib/my/gem.rb
      create  my-gem/lib/my/gem/version.rb
      create  my-gem/.rspec
      create  my-gem/spec/spec_helper.rb
      create  my-gem/spec/my/gem_spec.rb
      create  my-gem/.travis.yml
```

The change simply makes the order explicit for all the commands that has extra options:

``` shell
› bundle help gem
Usage:
  bundle gem GEM [OPTIONS]

Options:
  -b, [--bin=Generate a binary for your library.]
  -t, [--test=Generate a test directory for your library: 'rspec' is the default, but 'minitest' is also supported.]
  -e, [--edit=/path/to/your/editor]                                                                                   # Open generated gemspec in the specified editor (defaults to $EDITOR or $BUNDLER_EDITOR)
      [--no-color=Disable colorization in output]
  -V, [--verbose=Enable verbose output mode]
  -r, [--retry=Specify the number of times you wish to attempt network commands]

```