Bootstrap 4 restyling

[fv3rdugo]

After upgrading to bt4, we're going to refine some details

• [ ] colors. Evaluate a theme.
• [x] remove eye icon for not public machines
• [x] user menu in navigation not visible correctly
• [x] vm options settings, resize owner field
• [x] Page of the list of virtual machines, improve request messages
• [x] color button options is very clear

[fv3rdugo]

Some color themes to choose in:

• http://bootstrap.themes.guide/
• https://bootswatch.com/ It is only necessary to modify in header.html.ep the reference to bootstrap.min.css

[frankiejol]

moved to the roadmap in the wiki