Stop using the `--exact` flag when publishing packages with Lerna.
Stop using the `--exact` flag when publishing packages with Lerna.

This follows-up on f710fe46c90ce22ccc6611050ec21c42e0d833d4, to see what
happens when we allow wider ranges of versions in depended-upon packages by
utilizing the caret semantic-versioning operator (i.e. `^`).

While I wasn't convinced this was fail-safe, I still think that the changes
in f710fe46c90ce22ccc6611050ec21c42e0d833d4 add some value when _also_
applying this change.

In particular, in my current workflow, I'm publishing a new version of
Apollo Server using the `release:server` npm script, and it wants to also
publish new versions of `@apollo/gateway` and `@apollo/federation` merely
because they are depending on `apollo-server-core` and currently specify
their dependency without the caret semver operator.

Note: We'll need to wait until the publish after this to see what the
effects are (since the first publish will introduce the caret operator), but
let's see how this goes! 🧪

cc @trevor-scheer

apollostack/apollo-server