Ability to customize project colors on dashboard

[alanhamlett]

Currently we fix language colors to the same as GitHub, but we should allow customizing project colors.

[JalilArfaoui]

Maybe we could use the .wakatime-project file. Currently this file only support one line which is the custom project name.

We could support further settings like so:

.wakatime-project

projectName
color:#ff5733

And then dashboard would use this color for this project in all charts.