Only run docker in integration with cache

.travis.yml

@@ -3,9 +3,11 @@ language: node_js
 services:
   - docker
 before_install:
-  - docker pull junderw/bitcoinjs-regtest-server
-  - docker run -d -p 127.0.0.1:8080:8080 junderw/bitcoinjs-regtest-server
-  - docker ps -a
+  - if [ $TEST_SUITE = "integration" ]; then
+      docker pull junderw/bitcoinjs-regtest-server &&
+      docker run -d -p 127.0.0.1:8080:8080 junderw/bitcoinjs-regtest-server &&
+      docker ps -a;
+    fi
 node_js:
   - "8"
   - "lts/*"

test/integration/_regtest.js

@@ -71,7 +71,7 @@ async function faucet (address, value) {
         }
       )
 
-    await sleep(randInt(50, 150))
+    await sleep(randInt(10, 40))
 
     const results = await unspents(address)