Prevent a crash during path verification

Swallow TFS exceptions for this non critical part of the clone process...

Permit to clone a branch and use git-tfs even when, due to a bug in TFS,
TFS is broken and return an error TF14045 when asking for branches.
update fetch documentation
correct typos in all command options
Merge pull request #556 from pmiossec/documentation

Documentation
Merge pull request #557 from pmiossec/prevent_crash_during_branch_verification

Prevent a crash during path verification