Update README.md

Added troubleshooting for intermediate SSL certificates
Update README.md
Update README.md
Added note about empty constructor for custom MessageRepositories.
add getProperty to GlobalConfiguration
Merge pull request #188 from descala/add_properties_getter

add getProperty to GlobalConfiguration
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' into custom_message_repository
use new getProperty method instead of getProperties
give priority to EndpointID over PartyLegalEntity/CompanyID again, unless it starts with ZZZ, closes #4681, #4712