Avoid to use cycle-my-theme at startup to speed up the loading

Manually create the solarized themes in order to have the
dark theme loaded last
Prefix theme related functions with spacemacs/
Fix init of Solarized theme
Uneeded creation of an untitled buffer at startup

In order to reduce even more the boot time of Spacemacs
Now we keep the focus on the *scratch* buffer at startup
Remove uneeded installation steps
Add .spacemacs template