throw exception on failing api calls

Makefile.PL
 - Add Carp as a dependency
 - Add Test::Exception as a build dependency

lib/Net/Amazon/EC2.pm
 - New attribute to control which behaviour the user wants
 - Documentation

t/03_failing_calls.t
 - Tests for the new behaviour
Merge pull request #9 from miquelruiz/master

Throw exception instead of return an error
Parse tagsets on volumes
Merge pull request #10 from ByteInternet/fix-describe-volumes-tagset

Parse tagsets on volumes
Permit modify_instance_attribute to take a HASHREF
Prep for 0.19 release
Improve describe_tag (RT#76139 and #76140)
Update Changelog for 0.19
Update t/02_live.t for return_errors
Treatment of no XML responses

 - Check if the Content-Type of the HTTP response is 'text/xml'.
 - Set an XML with errors when the response fails with a 500 or 300 code.
 - Since the error message can contain XML, it is now wrapped in a CDATA.
 - Check for XML parsing errors.
Merge pull request #11 from miquelruiz/master

Tests failing when a web server is running in localhost
Stop failing test when server listens on port 80
OK, really 0.20
add support for VolumeType and Iops to EBS volumes; add support for EbsOptimized attribute for instances
add EbsOptimized attribute to test for run_instances
update API version to 2012-07-20
silence an uninitialized warning in test
Merge pull request #12 from stevecaldwell77/master

Provisioned IOPS for EBS Volumes
Allow undef in TagSet values RT #80071
DeleteSnapshot does not take an array (GI #13)