Release v1.0.0

Finally release 1.0.0 to RubyGems.

Please refer to the updated README and CHANGELOG.

#123: Add thread safe method to query resources - @pedelman.
#121: Update product resources and examples - @pedelman.
#122: Update order resources and examples - @pedelman.
#120: Add attributes to store information resource - @pedelman.
#119: Update customer address - @pedelman.
#117: Update banner example - @pedelman.
#118: Update gift certificate example - @pedelman.
#116: Update BlogTag resource - @pedelman.
#115: Update BlogPost resource - @pedelman.
#113: Update SKU resource per developer docs - @pedelman.
#103: Add banner & gift cert resources - @bc-AlyssNoland.
#101: Fix #100 when exception and env.body is a string. - @gregory.
#89: Complete rewrite of Bigcommerce API Client. - @pedelman.