Clear up inconsistencies in test suite

[hoelzro]

The test suite's conventions vary from directory to directory. For example:

• t/host/plugin/storage tests begin with 00, but t/anyevent-webservice-sahara tests begin with 01.
• t/host/plugin/storage tests begin with a number, but t/client tests do not.
• Our storage base test class is Test::Sahara::Storage, but for configuration it's SaharaSync::Config::Test.