add .coverage file to .gitignore
Implement proper error-checking in GetSubscriptionsMethod
Implement proper error-checking in RegisterItemsMethod
Check Processes in Linux Plugin

  - proc.max
  - proc.num
  - proc.running
  - proc.zombie
Add get_type() function to identify DB backends

  - Fix some exception-messages in the AbstractDBProvider
Improve coverage for test_AbstractDBProvider
Read DBConnection from server.conf

  - Provide it to PublishValuesMethod