Memory example not working with latest graphql-tools

[acoreyj]

The memory example uses rollup, unfortunately the latest graphql-tools has circular dependencies that result in bad js for the browser.

I opened an issue at graphql tools as well. ardatan/graphql-tools#924

The fix was to downgrade the graphql-tools version which makes the memory example work, opened this issue so it can be upgraded if this is fixed in the future.