Update README
Export method ToSnake and SnakeToUpperCamel
Add basic support for DEFAULT values
Simplify set field value
Merge pull request #170 from chr4/master

Add basic support for DEFAULT values
Support inline condition when Delete
Fix typo
Refact untils.go
Fix check HasColumn for sqlite3
Fix check HasColumn for sqlite3
Refact tests
Fix remove index for sqlite and postgres
Refact tests
Refact tests
Write stub code for Many2Many
Refact parse SQL tag, set default size to 255
Use tag  to set primary key
Don't sort by primary key if it doesn't exist in First/Last
Use JoinTable instead of ForeignKey
Save many to many relations into join table