Generate human readable IDs for client URLs (#77)

Based on @FranzSkuffka's suggested enhancement in PR 207 on
localtunnel/localtunnel
(https://github.com/localtunnel/localtunnel/pull/207), this PR uses the
"human-readable-ids" package to generate IDs of the form
"adjective-noun-number". These IDs are easier to remember and arguably
more useful in testing since they can be retyped without copying and
pasting.

Some sample IDs generated by this package are:

* heavy-puma-90
* grump-walrus-64
* purple-starfish-58
* nasty-seahorse-9

yarn.lock

@@ -615,6 +615,12 @@ http-signature@~0.11.0:
     assert-plus "^0.1.5"
     ctype "0.5.3"
 
+human-readable-ids@1.0.3:
+  version "1.0.3"
+  resolved "https://registry.yarnpkg.com/human-readable-ids/-/human-readable-ids-1.0.3.tgz#c8c6c6e95085ccb668087b7dd767834e26ca26d4"
+  dependencies:
+    knuth-shuffle "^1.0.0"
+
 indent-string@^2.1.0:
   version "2.1.0"
   resolved "https://registry.yarnpkg.com/indent-string/-/indent-string-2.1.0.tgz#8e2d48348742121b4a8218b7a137e9a52049dc80"
@@ -733,6 +739,10 @@ keygrip@~1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/keygrip/-/keygrip-1.0.2.tgz#ad3297c557069dea8bcfe7a4fa491b75c5ddeb91"
 
+knuth-shuffle@^1.0.0:
+  version "1.0.8"
+  resolved "https://registry.yarnpkg.com/knuth-shuffle/-/knuth-shuffle-1.0.8.tgz#929a467b0efd8d297bdcf318ca988a9f1037f80d"
+
 koa-compose@^3.0.0:
   version "3.2.1"
   resolved "https://registry.yarnpkg.com/koa-compose/-/koa-compose-3.2.1.tgz#a85ccb40b7d986d8e5a345b3a1ace8eabcf54de7"