Add link to maven repo lookup (where appropriate)

[moxious]

The main sonatype repository provides a simple link for checking whether a repo contains a given JAR, by SHA1 hash.

Example URL: https://repository.sonatype.org/service/local/lucene/search?sha1=df4fa6b3e1e9fba69a92c269c8c982c577fb3f97

It would be trivial and also possibly useful to include in the webapp the option of checking this repo; this allows you to backtrack and discover the maven POM dependency language associated with that JAR. It also allows users to only have a hash, and end up being able to discover groupId, artifactId, and version.