Fixed SheetStacks generated by measure_cog
Applied compatibility fixes for recently merged DataViews pull request
Moved contents of command/analysis.py to analysis/command.py

Now that featuremapper exists as a separate project, all remaining
analysis commands can be moved to topo.analysis in order to avoid cyclic
imports (e.g for setting up Collector hooks). The file
topo/command/analysis.py has been kept for legacy support.
Removed deprecated version of Collector
Updated measure_cog to return an AttrTree
Updated measure_cog to use measurement_storage_hook
Configured storage and Collector hooks for measure_cog
Added .gitattributes for git archive support with param.Version
Disabling measurement storage hooks in IPython Notebook