build: workaround openjdk 7 crypto issue

Author: ifedapoolarewaju

.travis.yml

@@ -3,6 +3,12 @@ jdk:
 - openjdk6
 - openjdk7
 - oraclejdk8
+sudo: required
+before_install: # Work around missing crypto in openjdk7
+  - sudo wget "https://bouncycastle.org/download/bcprov-ext-jdk15on-158.jar" -O "${JAVA_HOME}/jre/lib/ext/bcprov-ext-jdk15on-158.jar"
+  - sudo perl -pi.bak -e 's/^(security\.provider\.)([0-9]+)/$1.($2+1)/ge' /etc/java-7-openjdk/security/java.security
+  - echo "security.provider.1=org.bouncycastle.jce.provider.BouncyCastleProvider" | sudo tee -a /etc/java-7-openjdk/security/java.security
+
 matrix:
   allow_failures:
   # https://github.com/square/okhttp/issues/528