v0.7.0

TrajectoryOptimization v0.7.0

Diff since v0.6.2

Closed issues:

• Incorrect Dense Costs on v0.7 (#66)
• Get rid of t0 and tf in Problem since these are stored in the trajectory (#68)
• Update documentation for TrajOpt (#70)

Merged pull requests:

• V0.7 (#61) (@bjack205)
• Separate dynamics (#64) (@bjack205)
• Multiple models (#65) (@bjack205)
• V0.7 lqr objective bugfix (#67) (@jbwillis)
• Docs and refinements (#69) (@bjack205)