remove excessive binding

In a few places there are tons and tons of bind calls to ensure
'this' means what we think it is. This patch removes these in favor
of declaring a single 'self' variable, for the sake of readability
add test describing skip behavior

For completeness, this test guarantees that if skip is called in
a "before" hook, that the actual action will be skipped as well.
print stack traces on test errors

This includes a line for our support fixture that always enables
stack traces in chai when an error occurs.
add test case for initializing without sequelize

This adds a test case verifying that we throw an exception when
epilogue has been initialized without a sequelize instance.