Don't print first page of entries, correctly add first page of entries

* The first page of entries was stored as an array within the larger
  array of entries, which meant the results were unusable.
* There's no need to `puts` the entries, that was a debugging artifact
Add Statistics Class, uses APIClient to get statistics on the entries

* The currently supported list of statistics are:
  * average per day of the week: how many hours do you log on each day
    of the week, on average?
    * # of (un)billable entries and hours (and avg. hours)
    * total # of entries and hours (and avg. hours)
  * average per month: how many hours do you log each month, on
    average?
    * # of (un)billable entries and hours (and avg. hours)
    * total # of entries and hours (and avg. hours)
  * average per month in time: how many hours did you log in a month
    over the course of the time?
    * # of (un)billable entries and hours (and avg. hours)
    * total # of entries and hours (and avg. hours)
  * average per project: how many hours did you log in a project?
    * # of (un)billable entries and hours (and avg. hours)
    * total # of entries and hours (and avg. hours)
  * average per tag: how many hours did you log using a tag?
    * # of (un)billable entries and hours (and avg. hours)
    * total # of entries and hours (and avg. hours)
  * average per tag combination: how many hours did you log using a
    particular set of tags?
    * # of (un)billable entries and hours (and avg. hours)
    * total # of entries and hours (and avg. hours)
  * average per entry type: how many hours did you log for each type
    of entry?
    * total # of entries and hours (and avg. hours)
* The API results are cached until the params are updated, in case the
  user wants to massage the data in specific ways.
Add statistics to Rake console, fix debugger statement, add `@stats`