New tutorials: write section to walk through installing and uninstalling a package

(For more information about this issue, please see #194).

We need a short section to follow the package sources section (see #200) (i.e., as its own file). It should satisfy the following goals:

• walk through installing a package with pip
• verifying that the package is installed (e.g., with an import statement or running a script)
• upgrade with the (--upgrade/-U switch), even if it doesn't actually do anything
• walk through uninstalling a package (again, with pip)

This should be a largely step-by-step process, explaining each step in turn.

When opening pull requests for this issue, please submit to the develop branch. If you have questions that concern contributing more generally, please use issue #194. Otherwise, feel free to comment with questions or feedback. Thanks!