Filter bundle related lines from backtraces.

This cleans the backtraces shown for failing examples. Works with both RSpec 2 and RSpec 3 (and should degrade gracefully for RSpec 1).

Before:
    ./spec/controllers/people_controller_spec.rb:18 :in `block (3 levels) in <top (required)>'
    /Users/stefan/Library/Application Support/Avian/Bundles/RSpec.tmbundle/Support/lib/rspec/mate/runner.rb:61 :in `block in run'
    /Users/stefan/Library/Application Support/Avian/Bundles/RSpec.tmbundle/Support/lib/rspec/mate/runner.rb:58 :in `chdir'
    /Users/stefan/Library/Application Support/Avian/Bundles/RSpec.tmbundle/Support/lib/rspec/mate/runner.rb:58 :in `run'
    /Users/stefan/Library/Application Support/Avian/Bundles/RSpec.tmbundle/Support/lib/rspec/mate/runner.rb:18 :in `run_file'
    /tmp/textmate-command-60237.rb:3 :in `<main>'

After:
    ./spec/controllers/people_controller_spec.rb:18 :in `block (3 levels) in <top (required)>'
 Fix deprecation (and formatter problem) in RSpec 2.14

RSpec 2.14 has both `backtrace_clean_patterns` and `backtrace_exclusion_patterns`. Using the former generates a deprecation message, which somehow also disables the textmate formatter.
Merge pull request #74 from die-antwort/filter-bundle-backtrace

Filter bundle related lines from backtraces.