New features
[4dd93aa] Added a Date Picker form field to show how to define custom types (@yceruto)
[e2d723c] Added an example about how to use multiple form buttons (@voronkovich)
[1e26a23] Added AppVeyor configuration for testing on Windows systems (@EmanueleMinotto)
Minor changes
[b4f82a7] Updated dependencies to Symfony 2.7.5 (@bocharsky-bw)
[66bfc56] Updated Brazilian Portuguese translation (@davialexandre)
[be40768] Updated German translation (@xabbuh)
[773a811] Updated Russian translation (@bocharsky-bw)
[c542a0a] Updated Ukrainian translation (@bocharsky-bw)
[6e4e20b] Updated Dutch translation (@Fbeen)