Fix Rake failure in projects importing tabula-extractor

In projects importing tabula-extractor, running `rake test` terminated with `NameError: uninitialized constant LogManager` because the class `java.util.logging.LogManager` was imported with `import` instead of `java_import`. `java.util.logging.Level`, on the following line, was also imported with `import` and caused the same error after the `LogManager` error was fixed. Searching tabula-extractor, these were the only uses of `import`. `java_import` is used throughout the rest of the project. `rake test` ran as expected after replacing both `import` statements with `java_import`.

References:
* Using a Java Class Without The Full Path Name
  https://github.com/jruby/jruby/wiki/CallingJavaFromJRuby#using-a-java-class-without-the-full-path-name
* loading rake breaks import
  http://jira.codehaus.org/browse/JRUBY-3171
Merge branch 'rake-uninitialized-constants' of https://github.com/sxren/tabula-extractor