Fix maven warning and travis build

Travis build looks to not be able to run e2e tests. This pull request disable e2e tests by default and add a specific profile (ie. e2eTests) to run them.

```
// Build with no tests
mvn clean install -DskipTests

// Build with tests and no e2e tests
mvn clean install 

// Build with all tests
mvn clean install -Pe2eTests
```

Also:
* Fix the list of maven warning during building (due to missing version number or duplicated deps)
* Set compiler target to 1.7 (as Lucene 4.9 depends on it)