DEV: Converted try/except functions to more appropriate if/elif
DEV: Converted try/except functions to more appropriate if/elif

While the original try/except function series worked for the metadata
dictionary population that I was attempting, the use of if/elif
is more appropriate since try/except expects an exception to be raised
if, or when the try function fails. Since I am simply reading the
original header string and populating a new metadata dictionary the
use of if/elif is more appropriate.

licode/scikit-xray,tacaswell/scikit-beam,CJ-Wright/scikit-beam,tacaswell/scikit-xray,Nikea/scikit-xray,yugangzhang/scikit-beam,ericdill/scikit-xray,licode/scikit-xray,ericdill/scikit-xray,tacaswell/scikit-beam,Nikea/scikit-xray,CJ-Wright/scikit-beam,CJ-Wright/scikit-beam,tacaswell/scikit-xray,celiafish/scikit-xray,scikit-xray/scikit-xray,licode/scikit-beam,danielballan/scikit-xray,Nikea/scikit-xray,tacaswell/scikit-xray,scikit-xray/scikit-xray,danielballan/scikit-xray,scikit-xray/scikit-xray,hainm/scikit-xray,licode/scikit-xray,danielballan/scikit-xray,yugangzhang/scikit-beam,giltis/scikit-xray,tacaswell/scikit-beam,hainm/scikit-xray,ericdill/scikit-xray,licode/scikit-beam,celiafish/scikit-xray,giltis/scikit-xray,yugangzhang/scikit-beam,celiafish/scikit-xray,hainm/scikit-xray,giltis/scikit-xray,licode/scikit-beam