Impose a minimum version on rbt patch with SVN

Review Request #7097 — Created March 20, 2015 and submitted — Latest diff uploaded

Information

RBTools
release-0.7.x

Reviewers

The svn patch command was added in SVN 1.7.0 (1). We now check the
version of svn prior to attempting to execute svn patch and report
to the user that their version of svn does not support the patch
command if it is less than 1.7.0.

(1): https://subversion.apache.org/docs/release-notes/1.7.html#patch

Ran unit tests.

Able to run rbt patch when using SVN 1.7.0 and above. Not able to
run rbt patch when using SVN prior to 1.7.0.