Remove delete repository index statement

In order to work towards a continuous repository harvesting I have
removed the delete index statement for the repository type.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Start to move metadata record into its own field

In order to address issue platzhirsch/metadata-census#22 I started to
move the original metadata record into its own field. Also, I have
removed a deprecated method.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Add logging statements

In order to make the harvest process a little bit more transparent I
simply added two logging statements.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Add date attribute to record harvest time

For the versioning the timestamp when the harvesting was performed needs
to be recorded. This will be done by using this date attribute. Although
more might follow.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Comment catalog.data.gov out

The US CKAN data catalogue cannot be used through the API at the moment
or at least not to my knowledge. I will investigate this, but for the
time being I remove it from the list of harvest instances.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>