Update to Log4J 2 #106

[ttben]

Basically replace log4 v1 with v2, more efficient and with less memory overhead
I think it would be interesting to rerun PR 105.
WDYT?

[davisjam]

I would be surprised if changing log4 versions affected the results of #105, which I believe are more strongly influenced by loading a Git repository into memory. The memory usage amplitude might decrease but probably not appreciably.

[davisjam]

@ttben Does this PR have any backwards compatibility implications for existing projects that use RepoDriller?

[ttben]

Git repositories definitely weight more than log4j but logging performance can have a huge impact nevertheless IMO.

Since log4j2 is embedded in RepoDriller, I think they will have to rename log4j.xml to log4j2.xml. And I think that's it.

[mauricioaniche]

LGTM! Thanks, @ttben !

I'll merge this commit right now as we should move to log4j2. If it gets slower, we then see the next action (which can't be to rollback to log4j1)

[mauricioaniche]

We forgot to change the log4j.xml to log4j2.xml in the src/test folder. Just did it directly to the master branch.