Use backtrace_exclusion_patterns instead of backtrace_clean_patterns

Backtrace_clean_patterns is now deprecated, this uses the new
backtrace_exclusion_patterns method instead.

Closes #730

Signed-off-by: Sam Phippen <samphippen@googlemail.com>
Merge pull request #732 from samphippen/dont-use-deprecated-patterns

Use backtrace_exclusion_patterns instead of backtrace_clean_patterns