Added default search path for most recent version of MySQL

fix #1547

Use -DPORTABLE=1 to build a portable version

 * Refactored code out of common/ into servatrice/
 * added smtp client library
 * disable registration when connected
 * validate email address
 * send activation token via email

 * Always install “release” plugins
 * install only plugins actually used

fixes #411

+ added resources needed for servatrice logo
~ updated CMakeLists.txt to include the new resources

and add a method to guess the path of servatrice.ini

WIN: in the binary directory
OSX: in the app bundle’s Resources subdirectory
LINUX: in $PREFIX/share/servatrice

* Move all cmake-related files in a new “cmake” folder
* move nsis files in there, too, since they are templates parsed by cake
* retrieve git version once when cmake is run, and use it for both
creating version_string.h/cpp and for package naming

You won’t have to copy manually all the dlls in the release directory
anymore

Without this change, make install and make package would require “sudo”
under osx

Without this change, make install and make package would require “sudo”
under osx

* Remove cockatrice_HEADERS (obsoleted by automoc)
* Remove compilation flags definition and Qt4 finding calls
* Make use of CMAKE_INSTALL_PREFIX
* use INSTALL(TARGETS) in place of INSTALL(PROGRAM)
* Osx: create a proper application bundle
* Added comments