Synchronize get_all_snapshots() with current version of API
typo

s/immitates/imitates/
Re-raise the last exception in the current scope.

`raise` with no arguments finds the last exception in the active scope; this
is the correct way to re-raise an exception that is caught but not handled.
Raising the caught exception object obscures stack information (like line
number) that may be useful for debugging.
Tests for #1554, remove unneeded compatibility layer
- support ami registration with a snapshot ID
Added promote_read_replica.  Updated modify_dbinstance with optional new_instance_id parameter.
Tests for promote_read_replica and modify_dbinstance
added missing assert after last test
Fix parameter validation for gs
Merge pull request #1858 from zwilt/develop

Fix parameter validation for gs
Added initial wheel support.
Merge pull request #1850 from rjschwei/registerWithSnap

Update EC2 get_all_snapshots and registering an image with a snapshot. Fixes #1850.
Merge pull request #1857 from bpennypacker/promote_and_rename

Add RDS promote and rename support. Fixes #1857.