Use single quotes to quote string literals

Double quotes are allowed in MySQL by default, but not if ANSI_QUOTES are on.

See: http://dev.mysql.com/doc/refman/5.0/en/string-literals.html
Merge pull request #324 from Symplicity/ansi_quotes

Use single quotes to quote string literals
improve comments
MysqlAdapter::renameColumn keep column default

When renaming a column with a default value the default is removed after the rename, this proposal fixes that.
Merge pull request #325 from Alexssssss/patch-1

MysqlAdapter::renameColumn keep column default
psr-2
Treat PHINX_TYPE_BINARY columns as SQLServer Varbinary

`binary` columns in SqlServer have a maximum length of 8000 bytes. Change to `varbinary` to add support for arbitrary length blobs.
Merge pull request #331 from dakota/patch-2

Treat PHINX_TYPE_BINARY columns as SQLServer Varbinary
support table comment
Merge pull request #334 from triple-i/0.3.x-dev

support table comment
Merge branch '0.3.x-dev' of github.com:robmorgan/phinx into 0.3.x-dev
Merge branch '0.3.x-dev'
starting to improve docs