Bumped version to 1.5.0 for release

1.5.0 - Released 12/18/13
---
  * BREAKING CHANGE: The gem list in bootstrap['gems'] must be converted from a list of
    Arrays to a Hash in yaml definition files, please look at README.md
  * BREAKING CHANGE: Now supports common yaml definitions in addition to group definitons
    Therefore, file structure has changed:
    ./autoscale/groups/<group name>
    ./autoscale/common/<config name>.yml | ./autoscale/common/<folder name>/<config name>.yml
  * The functionality to apply common configs is optional and done so in order of the 'include' array,
    as it first checks 'include' in the group_def to see if it is including any common_defs. If it is,
    it will deep merge first common_def into the defaults and then will deep merge subsquent common_defs,
    if any. Last, it will deep merge the result with the group_def and concat any arrays.
  * Improved Rivet's CLI option parser. It now uses OpenStruct instead of a Hash for the options,
    has cleaner user error messages with cmd help displayed and supports exit status codes