Add header space for blockfile color journal

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Implement the colormap journal

We now write a section of the metapage before every colormap write, stating
what we are about to change. We recover the data when we open a blockfile.

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Correctly detect errors on last test

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Don't invert return value for blockfile_validate

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Correct color journal restoration logic

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Color journal tests

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Remove crc_test binary and add to .gitignore

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>