templates/flights: Added "Upload flight" button to list view
topbar: Removed top-level "Upload" link
templates/flights: Change upload button color

Put more emphasis on the button.
templates/flights: Change upload icon to cloud-upload
topbar: Add upload icon back to the topbar

Without the label, just the icon.
templates: Change upload icon back to upload-alt for now

People are used to that icon and removing the label in the topbar is
probably enough change for now.
Merge pull request #62 from Turbo87/upload-button

Added "Upload" button and removed "Upload" label from topbar