Revert "Adding some assertions to cope with weird null pointers I'm seeing"

Could these have caused a 10% slow-down?!

This reverts commit 10702732de72e3cede1f298bbcf9c8c9b31af1da.
Use logback logging

* tests shouldn't show all the print output
* better to capture to a folder adjacent to the repo

* by default, log to file (with times?) and console (undecorated)
* in tests, log only to file

Remark: Instead of capturing to:
/private/var/folders//j9/q_mfn8gs0w5c_t8hrp1xk2g00000gn/T/1380820596783-0/_sample-repos_huge10MBCommitMessage.git.zip-unpacked.bfg-report/2013-10-03T18-16

it would nice to copy it into target, if natural?:

target/2013-10/09/21-05/should-cope-with-crazy/

This actually does log to a file and the console..

Don't depend on ***Singleton*** LoggerFactory and LoggerContext!
...or your tests will be mush

Fixed the multitude of reports-dirs problem & simplify report-file naming
Optional instrumentation so you can see exactly what obj is being cleaned

Generalise to 'LoadHook' for Memo pre & post actions
RepoRewrite is now a class and not an object - let's us access their state
crazy last minute hacking