v0.5.0

MITgcm v0.5.0

Diff since v0.4.6

• merge joss paper branch
• eliminate Climatology dependency in test (Climatology depends on MITgcm)
• bump to version 0.5.0 (archived version that will be listed in JOSS paper)

Merged pull requests:

• fix typo (#135) (@briochemc)
• Joss paper (merging joss branch) (#136) (@gaelforget)