Prevent pushing to symbolic references
Fixes errors in geogit-console

- Exception when closing console
- Eexception when starting console in a folder that is not a geogit repo
Merge pull request #719 from volaya/console_fixes

Fixes errors in geogit-console
Merge pull request #705 from volaya/push_symbolic

Prevent pushing to symbolic references
Allow defining mandatory tags in OSM mappings
some typo and grammar fixes to osm.rst
Trees reulting from OSM mapping now use exact same CRS as canonical OSM trees