Fix: local variable 'symbol_layer' referenced before assignment error
(if styling is applied to line impact layer)
show only impact layer in legend as in previous InaSAFE versions
also handle case when impact layer not in the top of TOC
fix pep8 issues
Function for convreting (lon, lat) -> epsg code of the utm zone
Merge pull request #738 from AIFDR/coordinate_converters

Function for convreting (lon, lat) -> epsg code of the utm zone
Updated the branch with master.