Refactor TestAll test loop in data_test.go

Combine the three separate loops for DB creation, running setup
functions, and running tests into one loop.  Add a DB delete at the
end of each test for cleanup.

This groups output for each test together in one place.  It also has
the advantage of not running all DB creations and setup functions until
they're needed.
Merge pull request #922 from influxdb/data-test-loop

Refactor TestAll test loop in data_test.go
Fix #780 so that fill works with all aggregates
Refactor data_test.go to use Test* function names

Refactor integration/data_test.go to use Test* names for the tests
and remove the TestAll test case, which uses reflection to iterate
over all test functions.  Also, change the two SingleServerSuite
test functions in this file to DataTestSuite functions.

The DataTestSuite now conforms to standard Go / gocheck test
conventions.  Individual tests can be run.  Groups of tests can be
run by specifying patterns.  E.g.,

make integraton_test only=DataTestSuite

...will run all tests in data_test.go.  Or,

make integration_test only=DataTestSuite.Test.*Histogram

...will run all histogram related tests.

See the gocheck documentation for further details.