Remove libgtkspell-dev from build dependencies
pidgin-dev should now depend on libgtk-3-dev
Add libenchant-dev to Build-Depends
Use packages from sipe-collab PPA

libgstreamer1.0 -> libgstreamer1.4
libgstreamer-plugins-base1.0 -> libgstreamer-plugins-base1.4
libfarstream-0.2 -> libfarstream-0.2-sipe
Set PKG_CONFIG_PATH to search in /opt/gstreamer1.4
Make pidgin and finch use /opt/gstreamer1.4 RPATH