Parses the information contained in the message based on the
format that the message should be in. Returns null if the
format does not match the message
The format should be similiar to our response formats; e.g.
$loan <user1> <money1>
Allowed "special" codes:
- <user#> - Parses some text either of the format /u/username or username,
then strips the /u/ if it exists. The key is equal to the inside
- <money#> - Parses some number of the form $0.00, 0.00, $1,000.05 or 0.00$ then strips the
dollar sign and parses. The key is equal to the inside (e.g. money1)
This should only contain the part of the message that we want parsed and assumes its in the
right format