www: temporary submission form for datasets

* Adds submission form for datasets as a webdoc file under the help
  section. Handler processes the submission and sends an email
  to the curators.

  PS: Is not using the standard Invenio mailutils, requires a
  multipart email for the attachments.

* NOTE Temporary solution before moving to deposit.

Tested-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
Signed-off-by: Laura Rueda <laura.rueda@cern.ch>
www: data submission PEP8/257 updates

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
www: data submission UTF-8 support

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
Merge pull request #49 from jalavik/dataset-submission

Dataset submission