Add the github-linguist package

This commit only adds a single package and all of its transitive
dependencies. The github-linguist package will be used for counting
lines of code as a baseline for databases we are analyzing.

node_modules/fs-extra/docs/pathExists.md

@@ -0,0 +1,22 @@
+# pathExists(file[, callback])
+
+Test whether or not the given path exists by checking with the file system. Like [`fs.exists`](https://nodejs.org/api/fs.html#fs_fs_exists_path_callback), but with a normal callback signature (err, exists). Uses `fs.access` under the hood.
+
+- `file` `<String>`
+- `callback` `<Function>`
+
+## Example:
+
+```js
+const fs = require('fs-extra')
+
+const file = '/tmp/this/path/does/not/exist/file.txt'
+// Promise usage:
+fs.pathExists(file)
+  .then(exists => console.log(exists)) // => false
+// Callback usage:
+fs.pathExists(file, (err, exists) => {
+  console.log(err) // => null
+  console.log(exists) // => false
+})
+```