FIx license syntax for npm

[ceefour]

To be accepted by webjars/bintray. See also: https://docs.npmjs.com/files/package.json

Failed!
No valid licenses found. Detected licenses: Apache
The acceptable licenses on BinTray are at: https://bintray.com/docs/api/#_footnote_1
License detection first uses the package metadata (e.g. package.json or bower.json) and falls back to looking for a LICENSE, LICENSE.txt, or LICENSE.md file in the master branch of the GitHub repo.
Since these methods failed to detect a valid license you will need to work with the upstream project to add discoverable license metadata to a release or to the GitHub repo.

If you feel you have reached this failure in error, please file an issue: https://github.com/webjars/webjars/issues

Created NPM WebJar
Fetched NPM tgz
Generated POM
Converted dependencies to Maven
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Determined Artifact Name: bootstrap-treeview
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