Wrong arguments when calling safe_utils.getcallargs()

When calling safe_utils.getcallargs(), it will get all argnames from
definition of a function. As every function in Nova has a argument named
`context`, so argnames will always start with `context`.

In nova/exception.py#81, *args is a list of arguments which does not
start with
`context`, however, argnames starts with `context`, this will lead to a
mismatching when zip it into a dict.

Solution for this is that when calling getcallargs(), pass context as
one argument.

Change-Id: I4ce81e1862fb2d741f15747b04aa6bf1a2243364
Fixes: bug #1207153
Merge "Wrong arguments when calling safe_utils.getcallargs()"