fixed opened issues to stabilize buffalo v1

[sio4]

as a follow-up for gobuffalo/buffalo#2306, check and fix opened issues:

• fixed Generating a "pepsi" resource doesn't produce the desired outcome #37 by removing suffix rule of "pse" to "psis"
• fixed Pluralization and capitalization issues #20 (support pluralizing/singularizing for capitalized strings)
• ported better handling of multi-word idents #29 (multi-word support for pluralization) to singularize function
• added test case for Flect translating Field into Fieldren #33
• updated module dependencies.