More DataLad and OSF integration

• This release brings a variety improvements that jointly better utilize
  DataLad and OSF features

  • Add the ability to query a credential store via DataLad, when no
    credentials are found in environment variables

  • Add osf-credentials command to more conveniently set and reset
    OSF credentials for use by DataLad

  • create-sibling-osf can now create public projects

  • OSF projects are now of category data by default and another category
    can be set via create-sibling-osf --category

  • Assign default OSF project tags to location any and specific datasets
    via OSF search functionality

  • Add the ability to use OSF projects as git-annex exports or actual annex
    stores

  • Add git-remote-osf Git remote helper to use an OSF project as a regular
    Git remote, using osf://<projectid> URLs. Performance can be suboptimal
    when used with datalad push in DataLad versions up to 0.13.0 (repeated,
    avoidable Git repository uploads). Fixes have been queue for 0.13.1, and
    0.14.0.

  • Ability to datalad clone osf://<projectid> to publish and obtain entire
    datasets via OSF , without the use of a separate service for Git hosting

• API changes

  • Rename create-sibling-osf --sibling to -s/--name for uniformity with
    other such DataLad commands

  • Rename create-sibling-osf --mode {annexstore,exporttree} to
    --mode {annex,export} to match git-annex terminology

• Expanded test suite

  • Credential-less read-only access to public datasets

• Fixes

  • User/password authentication used user as password and failed

• Dropped dependency on 7z, archive and compression is now implemented via
  Python standard library functionality

• Major documentation overhaul to reflect the new features and changed behavior