Bump version to 0.2.5+sipe-1
Add -sipe suffix to package names
Use /opt prefix
Set environment variables to search in /opt/gstreamer1.4

PKG_CONFIG_PATH, XDG_DATA_DIRS and LD_LIBRARY_PATH.
Set DEB_SHLIBDEPS_INCLUDE in order to search in /opt
Set path for dh_shlibdeps
Updated d/libfarstream-0.2-2-sipe.symbols