snapshot/version file should have a .monticello extension

[dalehenrich]

I think that the monticello only files should have a .monticello extension ... I anticipate that there might be other meta-data files stashed around the package structure and putting extensions on all of the files/directories is probably a good idea...it's not like folks will every be typing these names...

[cdlm]

Since this is internal data, what about using .monticello as the filename to hide it from human eyes? Only problem I see is forgetting it when doing a manual add in git…

[dalehenrich]

Since there are several files involved I decided to move them all into a directory named monticello.meta ... for now