I did keep some "bare" except with catch all Exception: , while tried to disable
flake8 complaints where clearly all exceptions are to be catched

Fixes my incorrect fix in #598

That way, we will try to decode as default encoding (usually
utf-8), but allow ourselves to simply keep bytes that don't
match within the resulting unicode string.

That way, we allow for lossless decode/encode cycles while still
assuring that decoding never fails.

NOTE: I was too lazy to create a test that would verify it, but manually
executed https://github.com/petertodd/gitpython-unicode-error.

fixes #532

+ Mark all unused vars and other non-pep8  (PyDev) warnings
+ test_utils:
  + enable & fix forgotten IterableList looped path.
  + unittestize all assertions.
+ remote: minor fix progress dispatching unknown err-lines

+ FIX TestRepo.test_submodule_update():
  + submod: del `.git` file prior overwrite; Windows denied otherwise!
+ FIX TestRepo.test_untracked_files():
  + In the `git add <file>` case, it failed with unicode args on PY2.
Had to
encode them with `locale.getpreferredencoding()` AND use SHELL.
+ cmd: add `shell` into `execute()` kwds, for overriding USE_SHELL per
command.
+ repo: replace blocky `communicate()` in `_clone()` with thread-pumps.
+ test_repo.py: unittestize (almost  all) assertions.
+ Replace open --> with open for index (base and TC).
+ test_index.py: Enabled a dormant assertion. 

+ Cannot `index.path` into ENV, it is bytes!
+ The hook TC never runs on linux!
+ Unblock removal of odbfile in perf-large streams TC.
+ Attempt to unblock removal of submodule file by intensive cleaning.

more unblock files

+ HookException thrown on Popen, and were missed on Windows.
+ No SHELL on Popen??
+ Minor fixes:
  + Try harder to delete trees - no remorses.
  + Simplify exception reprs.
  + Unittest-ize test_index assertions.

+ FIX all Diff TCs.