4.0.4

New features

[265757c] Make the bootstrap JavaScript variable available on all backend pages (@michaelKaefer)
[8786bd8] Allow to filter the list of countries displayed in Country field (@javiereguiluz)
[d5b77c5] Allow to load assets conditionally based on page (both for CRUDs and fields) (@javiereguiluz)
[e504b00] Improve the "Welcome Page" and the docs about customizing dashboards (@javiereguiluz)

Bug fixes

[e99e0b7] Change the HTTP verb used to make Ajax requests in boolean toggles (@michaelKaefer)
[027eb34][f9d6e23] Minor tweak designs (@php4fan, @matteosistisette)
[ce52b9f][8281fd0][8f19245] Misc. doc fixes and improvements (@javiereguiluz)