Fix webpack transforms for different install methods

[jameshadfield]

The directory structure of npm dependencies is different
depending on whether auspice is installed from source, a
global npm install or a project's dependency. E.g. for webpack
to process the font-awesome dependency, then:
Global install & from source: ${__dirname}/node_modules/font-awesome
Project dependency: ${__dirname}/../font-awesome

This bug comes from #826 which specified the first of the above
two scenarios.

Tested with projects using auspice (incl client-side customisations)
via global npm auspice install, auspice as a npm dependency and auspice via npm link <path>

Note that this PR implements a short-term solution. In general, there are a a lot of
complex issues related to npm and using auspice to build custom bundles, including
but not limited to #689. I plan to write up a detailed issue for these shortly.

[tsibley]

@jameshadfield I think a simpler solution to this is to remove the include condition for file-loader all together:

diff --git a/webpack.config.js b/webpack.config.js
index 8c34bdf3..50b8b2de 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -118,13 +118,7 @@ const generateConfig = ({extensionPath, devMode=false, customOutputPath, analyze
         },
         {
           test: /\.(gif|png|jpe?g|svg|woff2?|eot|otf|ttf)$/i,
-          use: "file-loader",
-          include: [
-            ...directoriesToTransform,
-            path.join(__dirname, 'node_modules/font-awesome'),
-            path.join(__dirname, 'node_modules/leaflet'),
-            path.join(__dirname, 'node_modules/typeface-lato')
-          ]
+          use: "file-loader"
         }
       ]
     }

Not entirely sure why the include was there in the first place, but by removing it, I believe this lets the file-loader process any import which matches the test, not just those within the listed dirs. This seems like fine behaviour.

[jameshadfield]

Thanks @tsibley!