Associate a Kernel and Ramdisk

There are three ways that you can associate a kernel and ramdisk with an image.

This only applies to Linux images. Windows images do not use kernels or ramdisks.

You can associate a specific kernel and ramdisk identifier with an image at the euca-bundle-image step.
```
euca-bundle-image -i <vm_image_file> --kernel <eki-XXXXXXXX> --ramdisk <eri-XXXXXXXX>
```
You can specific kernel and ramdisk at instance run time as an option to euca-run-instances command.
```
euca-run-instances --kernel <eki-XXXXXXXX> --ramdisk <eri-XXXXXXXX> <emi-XXXXXXXX>
```
An administrator can set default registered kernel and ramdisk identifiers that will be used if a kernel and ramdisk are unspecified by either of the other options.