Extract non-bootstrap code from SpecEnvironment

Signed-off-by: Abhijit Hiremagalur <abhi@pivotallabs.com>
Make fixture path a global constant

Since it never changes and always has the same value

Signed-off-by: Abhijit Hiremagalur <abhi@pivotallabs.com>
Delete unused code

Signed-off-by: Abhijit Hiremagalur <abhi@pivotallabs.com>