Cleanup package metadata

[LinusU]

• Add files to not ship tests to npm
• Fix markdown linting errors
• Remove description from package.json, which will read it from the first line of readme.md instead
• Use github repository shorthand to fill in most pacakge.json fields

package content diff:

--- a	2019-02-13 14:08:37.000000000 +0000
+++ b	2019-02-13 14:08:55.000000000 +0000
@@ -1,49 +1,7 @@
 package.json
-.travis.yml
-example.js
 formats.js
 index.d.ts
 index.js
 LICENSE
 README.md
 require.js
-tsconfig.json
-.vscode/settings.json
-test/fixtures/cosmic.js
-test/json-schema-draft4/additionalItems.json
-test/json-schema-draft4/additionalProperties.json
-test/json-schema-draft4/allOf.json
-test/json-schema-draft4/anyOf.json
-test/json-schema-draft4/bignum.json
-test/json-schema-draft4/default.json
-test/json-schema-draft4/definitions.json
-test/json-schema-draft4/dependencies.json
-test/json-schema-draft4/enum.json
-test/json-schema-draft4/format.json
-test/json-schema-draft4/items.json
-test/json-schema-draft4/maximum.json
-test/json-schema-draft4/maxItems.json
-test/json-schema-draft4/maxLength.json
-test/json-schema-draft4/maxProperties.json
-test/json-schema-draft4/minimum.json
-test/json-schema-draft4/minItems.json
-test/json-schema-draft4/minLength.json
-test/json-schema-draft4/minProperties.json
-test/json-schema-draft4/multipleOf.json
-test/json-schema-draft4/not.json
-test/json-schema-draft4/nullAndFormat.json
-test/json-schema-draft4/nullAndObject.json
-test/json-schema-draft4/oneOf.json
-test/json-schema-draft4/pattern.json
-test/json-schema-draft4/patternProperties.json
-test/json-schema-draft4/properties.json
-test/json-schema-draft4/ref.json
-test/json-schema-draft4/refRemote.json
-test/json-schema-draft4/required.json
-test/json-schema-draft4/type.json
-test/json-schema-draft4/uniqueItems.json
-test/json-schema.js
-test/misc.js
-test/safe-regex.js
-test/schema-path.js
-test/typings.ts

package size diff:

--- a	2019-02-13 14:09:47.000000000 +0000
+++ b	2019-02-13 14:10:01.000000000 +0000
@@ -1,3 +1,3 @@
-package size:  23.6 kB
-unpacked size: 137.2 kB
-total files:   49
+package size:  9.8 kB
+unpacked size: 39.8 kB
+total files:   7

closes #57

[LinusU]

It's been a long while without any comments, merging this as-is ☺️

[LinusU]

Released as 🚢 2.20.0