Dependencies updates and some bug fixing

[mondus]

Targets

• [x] Update dependancies #162
• [x] Fix div by zeros #175
• [x] Fix gantt #146 and #168
• [x] Fix salary band drop down order #173
• [x] Flexible allocations #176
• [x] Home page warning #170
• [x] Better value of soon #169
• [x] Validation of service rate #158

[bobturneruk]

It's going to take me a while to properly check this - my django is not strong. For a faster review another team member might be better?