Avoid relative names in type checking messages

This also simplifies the error message by not showing the full
query. Only the offending expression is shown.
Removes check for unused field
Improves error message copy
Remove unused field altogether
Merge pull request #297 from thiagoarrais/pp-type-check-error-msg

Avoid relative names in type checking messages
Add test for handling of `and` with conditionals in `Validator`
Merge pull request #300 from lexmag/more-validator-tests

Add test for handling of `and` with conditionals in `Validator`
Link to hexdocs.pm
Return validation errors as maps
Closes #286
Change predicates to return `nil | binary`
Merge pull request #301 from lexmag/errors-as-map

Return validation errors as maps
Update README.md

Fix typo.
Merge pull request #307 from Chipairon/patch-1

Update README.md
Update poolboy
Try to to fix lock test race
Remove nils until we do type inference
Fix type comparison on update_all

Closes #310.
Mix tasks now use port if specified in ecto URL
Merge pull request #312 from stevedomin/steve-mix-use-port

Mix tasks now use port if specified in ecto URL