Project structure. Log capture. Exception matcher.

- Maven multi-module project with all dependencies and set up for OSS
Sonatype.
- Utility to capture logs as a JUnit rule. Binding for log4j, log4j2
and logback (+ tests).
- Utility to match exceptions using Runnables and Hamcrest (+ tests).
Improved .gitignore for Maven, Gradle, Java, etc.