[SPARK-4501][Core] - Create build/mvn to automatically download maven/zinc/scalac

Creates a top level directory script (as `build/mvn`) to automatically download zinc and the specific version of scala used to easily build spark. This will also download and install maven if the user doesn't already have it and all packages are hosted under the `build/` directory. Tested on both Linux and OSX OS's and both work. All commands pass through to the maven binary so it acts exactly as a traditional maven call would.
Yeah, I removed them to clear up the Jenkins logs. It would probably be
nicer as Patrick suggested if the bars were suppressed only when Jenkins is
executing the build.
On 2014년 12월 22일 (월) at 오후 5:32 Patrick Wendell <notifications@github.com>
wrote:

> In build/mvn
> <https://github.com/apache/spark/pull/3707#discussion-diff-22194686>:
>
> > +# Installs any application tarball given a URL, the expected tarball name,
> > +# and, optionally, a checkable binary path to determine if the binary has
> > +# already been installed
> > +## Arg1 - URL
> > +## Arg2 - Tarball Name
> > +## Arg3 - Checkable Binary
> > +install_app() {
> > +  local remote_tarball="$1/$2"
> > +  local local_tarball="${_DIR}/$2"
> > +  local binary="${_DIR}/$3"
> > +  if [ -z "$3" -o ! -f "$binary" ]; then
> > +    # check if we already have the tarball
> > +    # check if we have curl installed
> > +    # download application
> > +    [ ! -f "${local_tarball}" ] && [ -n "`which curl 2>/dev/null`" ] && \
> > +      echo "exec: curl -s ${remote_tarball}" && \
>
> I see - I think @nchammas <https://github.com/nchammas> removed these
> progress bars in 19f61c1
> <https://github.com/apache/spark/commit/19f61c165932059e7ce156da2c71429fa8dc27f0>
> for some other cases. I would actually like to have the progress bars
> because otherwise it's very confusing what is happening when developing
> locally. However, we can check whether AMPLAB_JENKINS is set, and not
> show them in that case. Similar to here:
>
>
> https://github.com/apache/spark/blob/daaca14c16dc2c1abc98f15ab8c6f7c14761b627/dev/run-tests#L80
>
> If you wanted to fix the other instance as well @brennonyork
> <https://github.com/brennonyork>, that would be great.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/apache/spark/pull/3707/files#r22194686>.
>