Add support for overriding template dir (#50)

Add optional '-template-dir' flag to 'gotestfmt' cli command that allows overriding of the default template lookup path. Defaults to './.gotestfmt' to maintain backwards compatability.
Simplify ciEnvironments mapping to easier support dynamic root template folder.
Update 'findTemplate' function to allow passing in a root directory path that is used for os filesystem lookups, but not for embed fs lookups.

Co-authored-by: Michael Engel <engel.michael@hotmail.de>

fixed issue #47 (#48)

2.4.0: Moving to GoTestTools

Fixes #42: incorrect output processing of in-test ok message

Fixes #39: Crash on syntax error output after legitimate output + go-…

…acc compatibility

2.3.0: Non-zero exit code on test failure

2.2.0: Test output formatters

This release adds the ability to use the -formatter option to run an external formatter for each test case and format the output.

2.1.0: Several bugfixes and a flag to show written test status by @Ma…

…rtinPetkov

Fixes #16: Non-verbose logging (#17)

2.0.0: Switching to JSON