Bugs about URL and percent-encoded ASCII string

[biluohc]

Sqlx's Version: 0.4.0-beta.1 and master.

Sqlx can't connect to DATABASE if the URL's password contains special characters that needs url-encoding now.

Maybe should use percent_encoding to decode it.

I use MySQL, buts other databases also have this problem.

https://github.com/launchbadge/sqlx/blob/master/sqlx-core/src/mysql/options/parse.rs#L26

pub fn query(&self) -> Option<&str>
Return the password for this URL, if any, as a percent-encoded ASCII string.

string in .env:  DATABASE_URL=mysql://root:Q3Mjg=@127.0.0.1/templatedb
Parsed URL: mysql://root:Q3Mjg%3D@127.0.0.1/templatedb
password: Q3Mjg%3D
Error:  error returned from database: 1045 (28000): Access denied for user 'root'@'172.17.0.1' (using password: YES)

Some other attributes of the URL are also like it, may have to watch for them, but the password easiest to have special characters.

Thanks.

[pymongo]

Fix in PR #630