PDBParser blank occupancy as 1
Handle blank lines in DSSP (closes Redmine 3441)
Improve assignment of PDB atom element from name.

Previously, hydrogens with a leading digit were given element ""
Test that PDBParser assigns "HE21" as a hydrogen
Also testing under PyPy 2.1 now.

Documentation change only, skip TravisCI tests [ci skip]
Some updates for Bio.motifs.jaspar