Move third-party pluggable transports licenses to /pluggable-transports/bundle.git

There is a new home for the PT bundle-building scripts that formerly lived in /flashproxy/doc.

https://gitweb.torproject.org/pluggable-transports/bundle.git

Let's move the licenses for M2Crypto, PyCrypto, zope, etc., etc., there (and change the makefile to match). These bundle scripts are where we're actually integrating and distributing all the third-party software, so it makes sense to keep the licenses there. Someone receiving a copy of e.g. obfsproxy doesn't need the e.g. zope license--that's only necessary in the bundle where we actually distribute zope.

The LICENSE files of flash proxy and obfsproxy can go back to only containing the licenses of flash proxy and obfsproxy.