Avoid assertion in allDocsQuery:options: when a docId isn't found.
Avoid assertion in allDocsQuery:options: when a docId isn't found.

When using `allDocsQuery:options:` with an array of docIds, a missing document will cause an 'Invalid parameter not satisfying: properties' assertion in `[TD_Body initWithProperties:]`.
cloudant/CDTDatastore,cloudant/CDTDatastore,cloudant/CDTDatastore,cloudant/CDTDatastore