Add Git tags to datasets

[psybers]

Git supports tagging commits. We need to keep this data (list of tags and their associated commit hashes) in our dataset.

Our code currently has a getTags() for Git, but it is never called anywhere. See:

compiler/src/java/boa/datagen/scm/GitConnector.java

Line 123 in 32521c5

public void getTags(final List<String> names, final List<String> commits) {

[nguyenhoan]

a873dfa