Adds some additional docs about the module parameters for s3
and ec2 modules.

Add some details in the docs about how the id parameter of the ec2
module behaves.

Remove the reference to the unused "termination_list" parameter
in the ec2 module. The instance_ids parameter is the one that contains
the list of instance ids to be terminated.

In the ec2 module, if an id is specified, check if there have been
any changes. If not, return changed=False

Fixes #3746

Boto blindly assumes the us-east-1 region if you don't hardcode a
region in it's config, so you could end up attempting to modify ELB's
in one region from a totally different region.  If a region isn't
specified then default to the region that the module is being run
within rather than the default us-east-1 region since it's a pretty
safe assumption that you intend to work on the ELB's within your
current region.

Also throw an error if a specified ELB instance doesn't exist.  The old
behavior would be to silently succeed with changed=false, so if you had
so much as a typo in the name of your ELB (or were in the wrong region
like my initial testing) you wouldn't get a clear indication that a
problem had occurred.

The timeout parameter of glance-image was not being parsed into a
numeric type, causing the following error when specifying timeout:

    msg: Error in creating image: unsupported operand type(s) for +: 'float' and 'str'

Revert "Added an elb_region parameter for interacting with the ec2 elastic load balancer to work with regions other than us-east-1"

This reverts commit 1264a5b4.

Added an elb_region parameter for interacting with the ec2 elastic load balancer to work with regions other than us-east-1

Changed shebangs that use /usr/bin/env to use /usr/bin/python and therefore be compatible with the ansible_python_interpreter variable.

Sometimes when using digital_ocean with wait=no I get the error "No ip is found".  But with wait=no I wouldn't expect there to be any IP, that gets allocated later.   However, looking at the code, it turns out that with even with wait=no it waits up to 10 seconds for an IP to be allocated.  We could wait longer, but with wait=no that seems like the wrong choice; it's easy enough to grab an IP later with a wait=yes command.

To make this change I removed the call to update_attr in @classmethod add.  An add is always followed by an ensure_powered_on which will do the update_attr if wait=yes.   It would be possible to instead do a call to update_attr with no retries and ignore the errors but I figured it would be better to be consistently not return an IP than to sometimes return it and sometimes not.   Inconsistent behaviour makes debugging deployment scripts very difficult.

The keystone client needs to be passed tenant_name when authenticating the
user/password way. Also it needs auth_url instead of endpoint.
This fix adds login_tenant_name as a module parameter which is consistent
with the other OpenStack modules.