Implement configuration options in EC2 backend for `image_id` and `instance_type`

[GoogleCodeExporter]

We need to add two configuration options for the `ec2` resource:

`<application>_image_id`: specify the image id to use for the application with 
name `<application>`

`<application>_instance_type`: specify the instance type to use for the 
application with name `<application>`

This is needed since different applications may requires different image id 
and/or instance type on the same resource.

Note that this is something very similar to what we are currently doing for 
`epilogue` and `prologue` scripts in batch-like resources.

Original issue reported on code.google.com by antonio....@gmail.com on 20 Feb 2013 at 11:37

[GoogleCodeExporter]

This issue was updated by revision r3513.

Also support `<application_name>_user_data` configuration option for 
`user_data` script.

    modified:   ../gc3libs/backends/ec2.py
    modified:   ../gc3libs/etc/gc3pie.conf.example

Original comment by antonio....@gmail.com on 20 Feb 2013 at 12:18

• Changed state: Fixed