Update source headers for version 0.9.5.2

Implemented abstract IsValidOnlyConnectionTester, which users may ove…

…rride to set a custom timeout.

Tweaked 0.9.5 release notes.

Fixed TestRefSerStuff.java to display long form of toString(...) [bro…

…ken when I recently switched to a short form by default]

Updated version headers, mchange-commons-java version.

Updated version headers to c3p0-0.9.5-pre8

Updated version of mchange-commons-java to 0.2.6.5 (not SNAPSHOT), c3…

…p0 source headers to version c3p0-0.9.5-pre7.

Update README.md

Updated version of dependency mchange-commons-java to latest.

Updated mchange-commons-java.version from SNAPSHOT to real 0.2.6.1