v0.58.0

Resolve issue with mount_points.readOnly bool and TF15 @darpham (#137)

what

• Add backwards compatibility with TF15 related to mount_points variable

why

• Incompatibility with TF15, root cause is unknown

references

• closes #136

comments/notes

• This will force users to specify the readOnly bool, previously where null was specified should now be false per AWS default
• Initially wanted to use default optional function within the variable, but this feature is only available in TF15