Calculate/display workshop, lesson #, lesson total

[terichadbourne]

Closes #62 and closes #70 by programmatically interpreting the route path to determine the shortname of the workshop ("Basics" or "Blog"), the lesson number, and the total number of lessons in the current workshop, without the author of a new workshop having to add this info explicitly. This also removes the need for the author to add a "last: true" property to make the button on the final lesson of the series work properly.

Note that the current solution will only work if we stick with our current pattern for paths (eg "/basics/02"), picking one-word shortnames for workshops. If we need to deviate from this pattern down the road, the "workshopShortname" calculated value will need to be adjusted, but this could be done without much difficulty if we consistently use hyphens or something like that to allow us to easily manipulate the string.

For now I'm doing a very simple presentation rather than a visual progress bar. (We can re-assess whether we want to do a progress bar once we build the ability to save state.) Here's the visual change you should see on each lesson page:

Updates:

• In Lesson.vue, calculate lessonNumber and workshopShortname
  from route path (removing trailing zeros in lesson number and
  capitalizing first letter of workshop name)
• In Lesson.vue, calculate total lessonsInWorkshop by
  incrementing path and checking if that route exists until it doesn't
• Calculate whether you're in the final lesson by checking if
  lessonNumber equals lessonsInWorkshop, so it's no longer
  necessary to pass a last: true (that property removed now from relevant
  lessons)
• In main.js, adjust route names for consistency to include shortname
  of workshop
• Update boiler.vue to match current needs
• Display "Workshop | Lesson X of Y" under lesson name