Fix lintian problems.

[mk23]

• [x] E: jmxproxy source: source-is-missing src/main/resources/assets/js/jquery.flot.js line length is 3134 characters (>512)
• [x] E: jmxproxy source: source-is-missing src/main/resources/assets/js/jquery.flot.navigate.js line length is 1893 characters (>512)
• [x] E: jmxproxy source: source-is-missing src/main/resources/assets/js/jquery.flot.resize.js line length is 1674 characters (>512)
• [x] E: jmxproxy changes: bad-distribution-in-changes-file stable
• [x] W: jmxproxy source: non-native-package-with-native-version
• [x] W: jmxproxy source: debhelper-but-no-misc-depends jmxproxy
• [x] W: jmxproxy source: virtual-package-depends-without-real-package-depends build-depends: java-compiler
• [x] W: jmxproxy source: build-depends-on-an-obsolete-java-package java-compiler
• [x] W: jmxproxy source: no-debian-copyright
• [x] W: jmxproxy source: ancient-standards-version 3.8.3 (current is 3.9.5)
• [x] E: jmxproxy: no-copyright-file
• [x] W: jmxproxy: extended-description-line-too-long
• [x] W: jmxproxy: extra-license-file usr/share/doc/jmxproxy/LICENSE.txt
• [x] W: jmxproxy: jar-not-in-usr-share usr/lib/jmxproxy-3.3.7.jar