erchef 1.2.1

Updated deps:

  eper
    2013-01-18 18d3175 Merge pull request #13 from massemanet/_blocking
    2013-01-18 ab65492 implement the blocking option

  chef_db
    2013-01-18 dca4773 Merge branch 'bookshelf_fix'
    2013-01-18 c8285f6 Rename checksum deletion functions
    2013-01-18 bcb232a Only delete un-referenced checksums