Lander

- Lander now creates and uploads a `metadata.jsonld` document alongside the landing page content (e.g., `index.html`).
This content can be ingested by other tools into the LSST Projectmeta database.
- Switch from metasrc to lsst-projectmeta-kit 0.3.0.
It's the same package, but the new and rebranded lsst-projectmeta-kit includes the ability to generate JSON-LD from an `LsstLatexDoc` object.

- Change known domain for DocuShare from `docushare.lsstcorp.org` to `docushare.lsst.org`.
This ensures that `ls.st` short links can continue to be verified.
- Create default values for `abstract_plain` and `title_plain`.
This fixes cases where the abstract is not set in the underlying LaTeX document.

- Update metasrc to 0.2.2 to resolve issues with auto-downloading Pandoc in Travis CI ([DM-12569](https://jira.lsstcorp.org/browse/DM-12569)).
- Update pytest to 3.2.5 and pytest-flake8 to 0.9.1 to fix incompatibilities in the floating indirect dependencies.

- Update metasrc to 0.2.1
- Use metasrc's `LsstLatexDoc.revision_datetime` to obtain the date of a document.
This method uses a combination of parsing the `\date` LaTeX command, looking at content
Git commits, and falling back to 'now' to get an appropriate timestamp.

- Update metasrc to 0.2.0.
This provides Pandoc integration for improved HTML rendering of content extracted from LaTeX documents.
- Improve how loggers are configured (warning level for third-party loggers, and info/debug levels for first-party LSST SQuaRE code).

- Update metasrc to 0.1.4.
This update provides improved LaTeX command metadata extraction.
([DM-11821](https://jira.lsstcorp.org/browse/DM-11821))
- Temporarily skip ls.st and DocuShare-related unit tests because ls.st links to DocuShare are broken due to the DocuShare upgrade.