Edits to make novice R lesson 01 more similar to novice Python lesson 01.

I have made edits so that the first R lesson more closely follows the Python lesson. It covers all the same topics save two:

  + Loading external packages - omitted because none of the operations in the lesson require loading an external package.
  + How to display three plots side-by-side - omitted because this is more complicated in R. This would require discussing how to set and reset `par` options, which is not a beginner topic.

Here's how you can quickly compare the two rendered files:

```
# clone bc repo
git clone git@github.com:swcarpentry/bc.git
# create and switch to new branch
git checkout -b review-pr
# add remote
git remote add jdb git@github.com:jdblischak/bc.git
# pull changes from my branch
git pull jdb 01-starting-with-data
# build site locally
make site
```
Then compare the rendered files  `_site/novice/r/01-starting-with-data.html` and `_site/novice/python/01-numpy.html`.
But that was not what @gavinsimpson was suggesting.

Gavin wrote:
> Do we want to continue with this or try to educate people on starting R where they want to work? Easiest way to do the latter is to touch my-analysis.R in the relevant folder then open my-analysis.R in R. I presume this works in RStudio?

This is how to accomplish that:

```
cd path/to/project
touch my-analysis.R
rstudio my-analysis.R
```

So to answer Gavin's questions: yes, RStudio supports this. However, the main downside of this approach is that it is so much easier to get the learners to just click on an icon on their desktop than try to get them to navigate to the correct working directory and launch RStudio. Also, I haven't tested it yet, but I don't know if the Windows Installer adds the RStudio executable to the path.