Add loader to iD editor

[vegeta999]

Closes #2680 Added preloader to the iD editor. Further enhancements:

1. We can give the transition property a thought to avoid sudden disappearance of the loader.
2. This is similar to the loader I suggested to add to login process, so if in future we add it then these files should be edited to avoid redundancy, mentioning it here #2371 .

@willemarcel please review !

[pantierra]

@willemarcel has this been fixed with #2753?

[vegeta999]

I have incorporated the preloader of 2753 to id editor, works fine !

[ramyaragupathy]

stale