Add support for waterline-schema >= v0.10.19

[dmarcelino]

waterline-schema v0.10.19 (a dependency of waterline) breaks sails-orientdb tests, check what changed v0.10.18 and update sails-orientdb accordingly.

• Add support for latest waterline v0.10.* / waterline-schema v0.10.*
• Remove waterline-schema from devDependencies (introduced in 3695331 as a workaround for tests to pass)
• Remove warning about waterline-schema from README.md