[TASKS] Added the "tire:index:drop" Rake task
[TASKS] Added the "tire:index:drop" Rake task

    $ rake -D tire:index:drop

Delete indices passed in the INDEX environment variable; separate multiple indices by comma.

Pass name of a single index to drop in the INDEX environmnet variable:

    $ rake environment tire:index:drop INDEX=articles

Pass names of multiple indices to drop in the INDEX or INDICES environmnet variable:

    $ rake environment tire:index:drop INDICES=articles-2011-01,articles-2011-02

Closes #199.

fabn/retire,ChapterMedia/tire,tklee/tire_shiphawk,Telmate/tire,fairfaxmedia/tire,brijeshgpt7/retire,doximity/tire,rubydubee/retire,mavenlink/retire,karmi/retire,HenleyChiu/tire,elbuo8/retire,dbose/retire,iamrahulroy/retire,alphagov/tire,zaharpecherin/retire,mikepb/tire,1776/tire,fcheung/tire