Upgrade jenkins baseline

In preparation for configuration as code plugin support

pom.xml

@@ -16,8 +16,8 @@
     </parent>
 
     <properties>
-        <jenkins.version>2.7.3</jenkins.version>
-        <java.level>7</java.level>
+        <jenkins.version>2.60.3</jenkins.version>
+        <java.level>8</java.level>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <powermock.version>1.6.6</powermock.version>
         <checkstyle.version>2.13</checkstyle.version>
@@ -62,16 +62,11 @@
         </developer>
     </developers>
 
-    <!-- get every artifact through maven.glassfish.org, which proxies all the artifacts that we need -->
     <repositories>
         <repository>
             <id>repo.jenkins-ci.org</id>
             <url>https://repo.jenkins-ci.org/public</url>
         </repository>
-        <repository>
-            <id>powermock-repo</id>
-            <url>http://powermock.googlecode.com/svn/repo/</url>
-        </repository>
     </repositories>
 
     <pluginRepositories>
@@ -85,7 +80,7 @@
         <dependency>
             <groupId>com.sonyericsson.hudson.plugins.gerrit</groupId>
             <artifactId>gerrit-trigger</artifactId>
-            <version>2.27.2</version>
+            <version>2.27.5</version>
             <optional>true</optional>
             <exclusions>
                 <exclusion>
@@ -165,10 +160,16 @@
             <version>0.10</version>
             <optional>true</optional>
         </dependency>
+        <dependency>
+            <groupId>org.jenkins-ci.plugins</groupId>
+            <artifactId>structs</artifactId>
+            <version>1.5</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.jenkins-ci.plugins</groupId>
             <artifactId>cloudbees-folder</artifactId>
-            <version>4.9</version>
+            <version>5.12</version>
             <optional>true</optional>
         </dependency>
         <dependency>
@@ -187,7 +188,7 @@
         <dependency>
             <groupId>org.jenkins-ci.plugins</groupId>
             <artifactId>credentials</artifactId>
-            <version>1.24</version>
+            <version>2.1.7</version>
             <optional>true</optional>
         </dependency>
         <dependency>
@@ -200,7 +201,13 @@
         <dependency>
             <groupId>org.jenkins-ci.plugins.workflow</groupId>
             <artifactId>workflow-aggregator</artifactId>
-            <version>1.4</version>
+            <version>2.5</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jenkins-ci.plugins</groupId>
+            <artifactId>scm-api</artifactId>
+            <version>1.3</version>
             <scope>test</scope>
         </dependency>
         <dependency>