Require Ant >= 1.8.2

Reportedly our build fails with Ant earlier incarnations.
Time to raise the bar.

Tested by temporarily setting the requirement to 1.8.5 and observing:

    % ant init
    Buildfile: /Users/jason/code/scala/build.xml

    desired.jars.uptodate:

    boot:

    init:

    BUILD FAILED
    /Users/jason/code/scala/build.xml:216: Ant version 1.8.5 is required. You are running Apache Ant(TM) version 1.8.4 compiled on May 22 2012
Convenience methods from Try[T] => {Future, Promise}[T]
SI-7862: MANIFEST.MF file for Scala sources

In order to be able to use published Scala jars as OSGi bundles in the
Eclipse build, Eclipse needs to match sources and binaries. That is
done by making source jars *source bundles*. This PR adds the required
manifest entries. Nothing else should be affected (file names remain
the same).
Merge pull request #2970 from dragos/improvement/source-osgi-headers

Fix SI-7862: MANIFEST.MF file for Scala sources
Merge pull request #2964 from retronym/topic/ant-18

Require Ant >= 1.8.2
Merge pull request #2949 from retronym/topic/future-from-try

Convenience methods from Try[T] => {Future, Promise}[T]