Make libeay32.dll and ssleay32.dll visible to pluggable transports

When we moved the pluggable transport executables into a PluggableTransports subdirectory, it broke some pluggable transport programs on Windows because they can't find the OpenSSL DLLs. To wit, it broke flashproxy-reg-appspot and flashproxy-reg-email, because they use the M2Crypto Python module, which relies on OpenSSL. The effect was that the windows bundle was falling back to flashproxy-reg-http.

This patch makes a copy of libeay32.dll and ssleay32.dll in the PluggableTransports directory. This works because the directory containing an executable is part of the DLL search path of the executable. http://msdn.microsoft.com/en-us/library/7d83bc18.aspx

Nothing is required for linux and mac because their RelativeLink scripts set LD_LIBRARY_PATH and DYLD_LIBRARY_PATH respectively to contain the directory with the OpenSSL dynamic libraries.

Alternative solutions may be to modify the PATH environment variable to include the directory containing tor.exe (which would have an effect similar to that of setting LD_LIBRARY_PATH in RelativeLink.sh), or to call SetDllDirectory (I don't know if SetDllDirectory is inherited by subprocesses).