BUG: fix unicode -> str cast in tslib

This should use format since calling str on a unicode string is a *bad* idea
because it may or may not repr correctly.
Merge pull request #3900 from cpcloud/tslib-fix

BUG: fix unicode -> str cast in tslib
DOC: release and whatsnew
BUG/CLN: remove infer_types
BUG: fix bug with replace when a compiled regex was passed but regex=False
TST: add tests for new com functions
TST: add test for is_list_like