Adds upper bound checking for flavor create parameters

The flavor-create API does validation that root_gb and
other integer values are positive integers but it doesn't
do an upper bounds check to make sure they aren't longs.
If a user tries to create a flavor with an integer value
that is bigger than an int, the python int() method
(used in the validation) will just convert it to a long but
the database model for InstanceTypes defines the column as
an Integer (not a BigInteger) and then the database has
to handle the value.

This changeset adds upperbounds checking for memory_mb,
vcpus, root_gb, ephemeral_gb and swap.

Also adds missing testcase for ephermal_gb validity

Change-Id: I63ef42e6befeff1edb81bc9caded2df2a4654b8c
Closes-Bug: 1243195
Merge "Adds upper bound checking for flavor create parameters"