Upgrade AskSage error reporting and portability

 In particular pass location of curl (used in sage call) from site.conf since the location can be different on different machines.
 Create error messages when debug is set to 1
Fix contextComplexJ so that it can be loaded in parserCustomization.pl, and so that it can allow or disallow each of the i and j notation independently.
Fix parserFunctionPrime.pl to handle names with primes properly in perl output (needed for answer checking, but not for display).  Apparently this file never worked (argh).
Fix List answer checker to set correct_ans_latex_string when parens have been removed.
Merge pull request #133 from paultpearson/patch-4

Update to _compoundProblem5_init

Small change.  I'll set up the pull request for develop myself.
Don't force functions to be of class parser::FunctionPrime (this messed up teh differentiation, since parser::FunctionPrime has parent parserFunction, and that overrides the D method).
Add a missing semicolon
Only remove parens when there are some, and make sure formulas returning lists also set correct_ans_latex_string.
Merge pull request #137 from dpvc/patch-primes

Fix parserFunctionPrime.pl to avoid error during answer checking.
Merge pull request #138 from dpvc/patch-list-checker

Fix List answer checker to set correct_ans_latex_string when parens have been removed.
Fix problem with error messages when a restricted input format is required.  Make sure constants display their TeX forms correctly.  Force the constant i into the given context so that it produces the proper class when evaluated.
Make sure the changes to teh context actually take effect.
Merge pull request #136 from dpvc/patch-complex-j

Fix contextComplexJ so that it can be loaded in parserCustomization.pl, ...

I tested this, both using global configuratoin changes and local ones.  I was able to require students to enter answers using i or j or either.  The display of equations, answers and correct answers all respected the appropriate flag.
Merge pull request #134 from mgage/develop_fixsage

Upgrade AskSage error reporting and portability
Fix 'fileFromPath not defined or not exported'  error
which occurs with perl 5.18.   the @ISA=qw(PGcore) statement should never have been there, but it does not seem to be causing the problem.  The workaround/fix for the moment is to fully qualify the function name as WeBWorK::PG::IO::fileFromPath.
Merge pull request #145 from mgage/master_IO_fix

Master io fix