Upgrade jar-tool to 0.1.7

This picks up a fix that prevented clean cross-fs
jar copies due to unclosed temprorary files.

Testing Done:
# observed jar-tool 0.1.7 ivy download and subsequent jarring (not cross-fs) work:
$ PANTS_DEV=1 ./pants goal clean-all killserver server
$ PANTS_DEV=1 ./pants goal binary bundle src/{java,scala}/::

Bugs closed: 198

Reviewed at https://rbcommons.com/s/twitter/r/475/

BUILD.tools

@@ -95,6 +95,6 @@ jar_library(name = 'scrooge-legacy-gen',
 
 jar_library(name = 'jar-tool',
             jars = [
-              jar(org = 'com.twitter.common', name = 'jar-tool', rev = '0.1.6')
+              jar(org = 'com.twitter.common', name = 'jar-tool', rev = '0.1.7')
             ])