Create optional Config

[k-capehart]

• New Config struct nested within Salesforce struct
• Defaults during authentication but can be optionally set afterwards

Examples

• consoleLogs - print log statements for status of long running jobs
• timeout - set global timeout for long running jobs
• bulkJobLogFileLocation - if not blank, then write bulk operation results to csv file at this location
• failOnPartial - for Collection methods, since allOrNone is false, optionally return individual record failures so caller doesn't have to check for them separately
• dmlLogLevel - none, info, warn, error - log dml errors for collections and composite operations