Remove python3 incompatible exception syntax.

Change-Id: I5f0687a83362ceebf03bae4a0a5b109aad7e5200
Move tests into project package.

There are several reasons for this. One is that the majority of
OpenStack packages behave this way. The second is that it makes writing
software that extends something easier to test (which is a clear usecase
for openstackclient) And third, tests/__init__.py implies a global
package named "tests" - which I'm pretty sure we're not providing.

Change-Id: Ic708ffd92aea78c2ffc1a8579af0587af4fca4ff
Merge "Remove python3 incompatible exception syntax."
Merge "Move tests into project package."