Fix write to index with msysgit bash

Closes #388.
Don't set global foldlevel

Without this change, Fugitive will routinely overwrite the global foldlevel. It shouldn't.
Fix unmatched parens in :Gmove
Add ability to query current Git version
Work around new status style in 1.8.5

Closes #393.
Merge remote-tracking branch 'upstream/master'