Add Jenkins CI (#15)

* intial jenkinsfile

* jenkinsfile pulls profile.json from credentials

* README updates

Jenkinsfile

@@ -0,0 +1,24 @@
+pipeline {
+    agent {
+        docker {
+            label "docker"
+            image 'maven:3-alpine'
+            args '-v /root/.m2:/root/.m2'
+        }
+    }
+    stages {
+        stage('Unit Tests') {
+            steps {
+                withCredentials([file(credentialsId: 'snowflake-kafka-connector-test-creds', variable: 'CREDFILE')]) {
+                    sh 'mv $CREDFILE profile.json'
+                    sh 'mvn test'
+                }
+            }
+            post {
+                always {
+                    junit 'target/surefire-reports/*.xml'
+                }
+            }
+        }
+    }
+}

README.md

@@ -5,3 +5,14 @@
 [![License](http://img.shields.io/:license-Apache%202-brightgreen.svg)](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
 Snowflake-kafka-connector is a plugin of Apache Kafka Connect.
+
+### Tests
+To run:
+```
+mvn test
+```
+
+#### Jenkins prerequisites:
+* Ensure `JENKINS_CONNECTOR_TESTS` database and `TEST` schema exist.
+* Grant `MONITOR, USAGE` for `PUBLIC` role on the database
+* Grant `CREATE*, MONITOR, USAGE` for `PUBLIC` role on the schema