Added npm install pre-step to generate docs to avoid the build failin…

…g when node_modules isn't already there

build.gradle

@@ -329,7 +329,13 @@ task signAll {
     dependsOn signJars, signThinJar, signShadowJar, signThinJarPom, signStandaloneJarPom
 }
 
+task npmInstall(type: Exec) {
+    workingDir 'docs-v2'
+    commandLine 'npm', 'i'
+}
+
 task generateApiDocs(type: Exec) {
+    dependsOn npmInstall
     workingDir 'docs-v2'
     commandLine 'npm', 'run', 'apidocs'
 }