reorganize content

[ErinBecker]

Ready for review and/or merge.

This PR does the following:

• switches order of episodes (fixes https://github.com/datacarpentry/organization-geospatial/issues/1)
• removes old episodes
• adds episode timings (fixes https://github.com/datacarpentry/organization-geospatial/issues/3)
• removes some information that I don't think is necessary for learners to get before starting the r-raster-vector lessons, to cut down on cognitive load (would appreciate comments from @datacarpentry/geospatial-maintainers on these cuts)
• adds keypoints and objectives for all episodes where missing
• cuts the first episode into 3 shorter episodes (raster, vector, and CRS)
• moves the content on organizing geospatial projects to the Introduction to R for Geospatial Data lesson (https://github.com/datacarpentry/r-intro-geospatial/pull/53).
• updates the index page to match the index for the Introduction to R for Geospatial Data lesson
• removes unused figure files
• removes old content in reference dealing with R concepts and vocab
• clarifies that there is no setup or data for this lesson
• renames lesson to "Introduction to Geospatial Concepts"
• adds challenges/discussions where appropriate
• standardizes formatting (e.g. list styles, header sizes) across episodes in lesson
• reorders content for overall flow
• removes references to specific Python packages and GUIs (this is overload for the learner since they aren't working with Python in this workshop (yet)) (fixes https://github.com/datacarpentry/organization-geospatial/issues/25)
• removes logos for geospatial software packages (I'm not sure of the legal issues with using their logos on our lessons)
• removes old episode files