Common ConnectionRefused class

Reason:
- Almost all projects using their own custom classes for exception
  which occures when API service refuses connection, or re-raises exception from httplib/requests.
Changes:
- Adding class ConnectionRefused, inherited from ClientException

Change-Id: I96385a50168dea17189149e9353ecaced6e15ab7
Fix typo in parameter documentation (timeutils)

Replace all occurrences of :params with :param
(matches http://sphinx-doc.org/domains.html#info-field-lists)

Change-Id: I72fbefcc7e176a962bfd4a6840a6237596900a3d
Merge "Fix typo in parameter documentation (timeutils)"
Merge "Common ConnectionRefused class"