Split manual.js into seperate JS files. Combine and minify JS with grunt-js plugin

Split manual.js into the following files:

    "${projectDir}/src/assets/js/googleAnalytics.js",
    "${projectDir}/src/assets/js/modernizr.js",
    "${projectDir}/src/assets/js/prism.js",
    "${projectDir}/src/assets/js/jquery.js",
    "${projectDir}/src/assets/js/anchorHighlight.js",
    "${projectDir}/src/assets/js/toggleImports.js"

minify.gradle build file contains 2 tasks: combineJs - to merge JS files into one all.js file, and minifyJs - to minify all.js into all.min.js file.

HTML files for manual as well as Javadoc API now have a reference to js/all.min.js file.