skip tests that require pandoc
Merge pull request #3792 from ivanov/skip-without-pandoc

skip tests that require pandoc
Deprecate flavor-level subclasses
Part way through adding 'flavor' support
Reflection of renames in template references
Changed reveal names
Added aliases to nbconvert commandline
Small bugfixes
Update exporter tests names
Updated tests to try flavors
latex.tplx->latex_basic.tplx & test changes
Fixed tests
Updated help string
Fixed errors after testing...
Added ability to export to a 'custom' format,
exposing the Exporter class
HTML-Slides -> Slides-Reveal
flavor=template
PDF is really a post-processor
Moved PDF logic into Post-Processor class
Updated example string for nbconvertapp.py