Edited usage of whitespace replacement to only be performed when inputting variables into job attributes table.  Otherwise, metagenome_name can be erroneously changed altered and cause job submission to fail.
Added error checking so that if add_valid_metadata function returns an error during job submission, the webpage tells the user about the error and sends the error message and job numbers to mg-rast rt system.
Merge pull request #341 from jaredbischof/develop

Changes to prevent job submission from failing and to let us know if job submissions do fail.