Fixed null reference on customData and new line in Email subject

[ctorx]

I found that the email error reporting was failing when Exceptional was configured using a connection string that resulted in a login failure.

2 issues discovered:

• Error.CustomData null reference when adding SQL custom data.
• MailMessage Subject Validation failed because the SQL Server Error message contained a new line

[ctorx]

Thanks, I allocated the dictionary earlier because I wasn't sure if there were other potential null reference use cases that didn't involve the SQL data that I encountered. Also, I think you may have missed the email subject fix in your commit.

[NickCraver]

Indeed I missed that one on the laptop - thanks!