Add Travis for CI (#62)

* Add a travis file

* Update readme

.travis.yml

@@ -0,0 +1,31 @@
+# Use docker-based build environment (instead of openvz)
+#sudo: false
+#dist: trusty
+
+# Use VM based build environment
+sudo: required
+dist: trusty
+
+language: java
+jdk:
+    - openjdk11
+
+env:
+  global:
+    - MAVEN_OPTS="-Xmx10244M -Xss128M -XX:MetaspaceSize=512M -XX:MaxMetaspaceSize=1024M -XX:+CMSClassUnloadingEnabled -XX:+UseConcMarkSweepGC"
+
+cache:
+  directories:
+      - '$HOME/.m2/repository'
+
+install: /bin/true
+
+before_script:
+# This seems to be required to get travis to set Xmx4g, per https://github.com/travis-ci/travis-ci/issues/3893
+  - export MAVEN_SKIP_RC=true
+# Sometimes things get restored from the cache with bad permissions. See https://github.com/travis-ci/travis-ci/issues/9630
+  - sudo chmod -R 777 "$HOME/.m2/repository";
+  - sudo chown -R travis:travis "$HOME/.m2/repository";
+
+script:
+  - mvn install

README.md

@@ -1,6 +1,10 @@
 HAPI FHIR - HL7 FHIR Core Artifacts
 ===================================
 
+[![Build Status](https://travis-ci.org/hapifhir/org.hl7.fhir.core.svg?branch=master)](https://travis-ci.org/hapifhir/org.hl7.fhir.core)
+[![Maven Central](https://maven-badges.herokuapp.com/maven-central/hapifhir/org.hl7.fhir.core/badge.svg)](http://search.maven.org/#search|ga|1|hapifhir/org.hl7.fhir.core)
+
+
 # Building this Project
 
 This project uses [Apache Maven](http://maven.apache.org) to build. To build: