explicitely document the options hash in the SYNOPSIS

(and remove the example specifically pointing at the 'git' option)
document a few more details about the option hash
fix code example
simplify the titles when documenting methods and functions

this simplifies linking to the documentation from pod,
and make it easier to keep the links working when the interface
changes

Thanks to Vincent Pit for the suggestion
update copyright year
better document the test_repository() options
add support for a 'clone' option in test_repository()
tests for test_repository() and its clone option
chdir back home before propagating the error from git

a failed chdir won't croak by warn, because the error from git is more
important to show than the error in chdir

in case git fails propagate the error
test with both possible repository url
no need to do the chdir dance around init and clone

the change of directories will be performed just before starting git,
thanks to the cwd option
Merge branch 'documentation'