Replace warning_exit by ValueError
BUG-FIX: MVATools.decompositon, MVATools.normalize_poissonian_noise and misc.eels.tools.estimate_noise_variance where assuming that after unfolding the fist data axis was the navigation axis what is not generally true. Added decomposition tests.
Merge pull request #115 from francisco-dlp/BUG-FIX_wrong_unfolded_assumption

Bug fix wrong unfolded assumption
Small style corrections
Fixes #121: spikes_removal_tool was causing a stack overflow
Merge pull request #122 from francisco-dlp/BUG-FIX_remove_spikes

Bug fix remove spikes
BUG-FIX: hdf5 files containing non-ascii characters were raising an exception on saving.
Merge pull request #123 from francisco-dlp/BUG-FIX_unicode_in_hdf5

BUG-FIX: hdf5 files containing non-ascii characters were raising an exce...
NEW: get_histogram

using the enhanced histogram of astroML
EHN: test
Merge branch 'get_histogram' into edslab

Conflicts:
	hyperspy/signal.py