add method for getting signed url for s3 bucket object

ref TheWeatherCompany/grid-api#374
update to rely on base context values for keypair

ref TheWeatherCompany/grid-api#374
Merge pull request #30 from TheWeatherCompany/autoscaling-tags

Added ability to tag auto scaling groups and have tags propagated to cre...
Merge pull request #29 from TheWeatherCompany/signed-s3-object-url

add method for getting signed url for s3 bucket object
Merge pull request #31 from TheWeatherCompany/autoscaling-tags

Added ability to update/remove tags on autoscaling groups.
add support for AWS IAM instance profile

Named "roleId" for core

Closes #32
Closes #33
Ref #TheWeatherCompany/grid-api#405
Add support for providerRoleId (Service Account / Instance Profile) for launch configurations

Closes #36
Ref TheWeatherCompany/grid-api/#412
Merge pull request #93 from TheWeatherCompany/support-iam-instance-profile

Support iam instance profile