Fix auto-loading of new Javadoc ZIPs

[mangstadt]

SEVERE: Uncaught exception thrown.
java.util.zip.ZipError: zip END header not found
at com.sun.nio.zipfs.ZipFileSystem.zerror(ZipFileSystem.java:1605)
at com.sun.nio.zipfs.ZipFileSystem.findEND(ZipFileSystem.java:1021)
at com.sun.nio.zipfs.ZipFileSystem.initCEN(ZipFileSystem.java:1030)
at com.sun.nio.zipfs.ZipFileSystem.(ZipFileSystem.java:130)
at com.sun.nio.zipfs.ZipFileSystemProvider.newFileSystem(ZipFileSystemProvider.java:139)
at java.nio.file.FileSystems.newFileSystem(FileSystems.java:390)
at oakbot.command.javadoc.LibraryZipFile.(LibraryZipFile.java:36)
at oakbot.command.javadoc.JavadocDao.addApi(JavadocDao.java:73)
at oakbot.command.javadoc.JavadocDao.access$200(JavadocDao.java:28)
at oakbot.command.javadoc.JavadocDao$WatchThread.add(JavadocDao.java:204)
at oakbot.command.javadoc.JavadocDao$WatchThread.run(JavadocDao.java:178)

[mangstadt]

Always seems to happen when uploading a ZIP directly into the Javadocs folder--like it's trying to read the ZIP before the upload has completed.

[mangstadt]

Low priority.

Have since switched to a system where the Javadoc info is not cached at all, so it loads the data from the ZIP files fresh every time. This means that there is no longer a need to monitor the Javadoc ZIP files for changes. Much simpler implementation. No noticeable difference in performance.