Upgrade BC to v1.57

[dfish3r]

v1.55 contains the following CVE:
CVE-2016-1000341
CVE-2016-1000346
CVE-2016-1000340
CVE-2016-1000344
CVE-2016-1000352
CVE-2016-1000338
CVE-2016-1000339
CVE-2016-1000342
CVE-2016-1000343
CVE-2016-1000345

Investigate upgrading to the latest version.

[dfish3r]

Fixed in 7051f6f