Fix incorrect exception order in _execute_request

_execute_request has a list of exception handlers to log various types
of errors with more specific error messages. Unfortunately, it catches
requests.exceptions.ConnectionError before requests.exceptions.SSLError,
but ConnectionError is a superclass of SSLError so the latter is never
invoked.

This change corrects the exception handling order, and enables the
bad-except-order pylint check now that the check passes.

Change-Id: I92bacd6088de5cbc170bc5c081a1db1baeec69e7
Closes-Bug: #1360970
MeteringPluginRpc: Fix crash in periodic_task

Restore __init__ chain which has been broken by
commit bdcc5a46d7776f50d5ae372798a913349629d2f6 .

Closes-Bug: #1396893
Change-Id: Ia1f0357b6726ac79a22ed1666eecebac33689aa1
Merge "MeteringPluginRpc: Fix crash in periodic_task"
Merge "Fix incorrect exception order in _execute_request"