closes #96, thanks to @twogee

The Apache release process no longer recommends using SHA1 checksums
for artifacts http://www.apache.org/dev/release-signing.html#sha1.
The commit here removes generation of SHA1 for Ant distribution artifacts.

Furthermore, the checksum generation for artifacts that we upload to
Maven is also now removed, since the Nexus instance generates those dynamically
when the artifacts are uploaded to Nexus as stated at
http://www.apache.org/dev/publishing-maven-artifacts.html#prepare-release :
"You don't need artifacts for your checksum files (if you create any) since Nexus
 will create MD5 and SHA1 checksums on the fly anyway."

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Merge tag 'rel/1.9.14' into 1.9.x branch

Tagging version 1.9.14 of Ant

I've decided to break backwards compatibility with the way I've
overridden runS. The "proper" way would have been to call the one-arg
version from the two-arg version so that subclasses overriding runS
would still get their method called. But I figured it to be extremely
unlikely that such subclasses exist.

This reverts commit 05bfffa247 and 506c3ab47a.