upgrade to POI 3.10

Upgraded the POI library to release 3.10.1 so that new functions such as IFERROR can be supported. 

**NB#** I had to swap the processing order of the functions in *new_area_reference* in area.rb to try for column references first as POI::AREA_REF.new(@ref) now seems to accept strings such as "numbers!$A" without failing but this causes a cell reference of "-1" further down the processing pipeline. 

I added a new sheet to various_samples.xlsx with an IFERROR call to test and a rspec test for it also. All tests passing my side on with following environment:

jruby 1.7.13 (1.9.3p392) 2014-06-24 43f133c on Java HotSpot(TM) 64-Bit Server VM 1.8.0-b132 +indy [darwin-x86_64]

java version "1.8.0"
Java(TM) SE Runtime Environment (build 1.8.0-b132)
Java HotSpot(TM) 64-Bit Server VM (build 25.0-b70, mixed mode)