Merge pull request #13 from dcsaszar/master

Error abstraction
inject swf dependency, deprecate usage of aws credentials
v 2.0.9
require rspec 2
Merge pull request #14 from infopark/feature-remove-credentials

Feature remove credentials
Typo and doc fix
Use master-workflow and master-activity types by default

The types are equal on all systems, so no need to duplicate
task_list_suffix_file becomes isolation_file

It will now be prepended to task list names and execution IDs.
Fixes #11
2.1.0