Update parse_resource.gemspec

This commit updates the gemspec with new requirements and test files by running `rake gemspec`.
Merge pull request #110 from sbonami/patch-1

Update parse_resource.gemspec
Fix to_time_in_current_zone deprecation warning

This commit fixes the `to_time_in_current_zone` deprecation warning by
replacing the old method with the new `in_time_zone` method.
Add validation callbacks to base module

This commit adds validation callbacks to the `ParseResource::Base`
module so that callbacks like `before_validation` are available.
Add to_pointer conversion to query where method

This commit adds a convert_arg method that takes care to convert where
arguments to a format Parse recognizes. This method converts Parse
Objects and Date/Time objects to Parse pointers.
Merge pull request #113 from sbonami/Add-to_pointer-conversion-to-query-where-method

Add to_pointer conversion to query where method
Merge pull request #112 from sbonami/Add-validation-callbacks-to-base-module

Add validation callbacks to base module
Merge pull request #111 from sbonami/Fix-time_zone-deprecation-warning

Fix to_time_in_current_zone deprecation warning