Updating bower file for main and build file to remove version numbers

The Bower file was missing a lot of information, especially the main file list. Main is important for use in projects that look for the main list of a package in order to determine what to files to make available to a tool such as an asset pipeline. This will allow doing something such as `// require jsPlumb/jquery.jsPlumb` instead of `// require jsPlumb/dist/js/jquery.jsPlumb-x.y.z`

The gruntfile's build task was updated to remove the version number from the compile file names. This will make updating  future versions in projects as easy as running an update task and testing as opposed to running the update, remembering to change the files to be included, and then testing. If for some reason the version number needs to be seen, the [grunt-header plugin](https://github.com/sindresorhus/grunt-header) can be used to add it as a comment to the beginning of the compiled code.