NUTCH 2940 Develop Gradle Core Build for Apache Nutch

[jbsimmon]

Added apache licenses to headers and updated wrapper; note that binary files will be removed and gitignored in future pull request anyways.

Thanks for your contribution to Apache Nutch! Your help is appreciated!

Before opening the pull request, please verify that

• there is an open issue on the Nutch issue tracker which describes the problem or the improvement. We cannot accept pull requests without an issue because the change wouldn't be listed in the release notes.
• the issue ID (NUTCH-XXXX)
  • is referenced in the title of the pull request
  • and placed in front of your commit messages surrounded by square brackets ([NUTCH-XXXX] Issue or pull request title)
• commits are squashed into a single one (or few commits for larger changes)
• Java source code follows Nutch Eclipse Code Formatting rules
• Nutch is successfully built and unit tests pass by running ant clean runtime test
• there should be no conflicts when merging the pull request branch into the recent master branch. If there are conflicts, please try to rebase the pull request branch on top of a freshly pulled master branch.

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[lewismc]

+1 please merge