Upgrade to Pegdown 1.2.0

Version 1.2.0 (2011-10-05)
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- Upgraded to parboiled 1.1.3
- Implemented parsing timeout, closes #42
- Fixed IndexOutOfBoundsException in ToHtmlSerializer, closes #39
- Changed parser to not swallow backslash before non-special characters, fixes #35
- Added test for fenced code blocks containing an empty line, closes #61
- Migrated all tests from TestNG to specs2
- Switched build tool from Apache Buildr to SBT

Version 1.1.3 (2012-10-16)
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Core & Java:
- Removed superfluous dependency on Scala library