Adding a test, fixing a test, adding nyc for test coverage reporting, updating README.md, returning .npmignore, updating .gitignore

Author: avoidwork

.gitignore

@@ -1,3 +1,5 @@
-node_modules/*
-.idea/*
-test/webpack/*
+.husky
+.nyc_output
+node_modules
+.idea
+test/webpack

.npmignore

@@ -0,0 +1,8 @@
+.github
+.husky
+.nyc_output
+src
+test
+.eslintrc.js
+.gitignore
+rollup.config.js

README.md

@@ -9,6 +9,19 @@ import {filesize} from "filesize";
 filesize(265318, {base: 2, standard: "jedec"}); // "259.1 KB"
 ```
 
+## Testing
+
+filesize has 100% code coverage with its tests.
+
+```console
+--------------|---------|----------|---------|---------|-----------------------
+File          | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
+--------------|---------|----------|---------|---------|-----------------------
+All files     |     100 |    95.52 |     100 |     100 |                      
+ filesize.cjs |     100 |    95.52 |     100 |     100 | 77-78,173,196,199,210
+--------------|---------|----------|---------|---------|-----------------------
+```
+
 ## Optional settings
 
 `filesize()` accepts an optional descriptor Object as a second argument, so you can customize the output.