[exporter/utils] mem conversion float err

[abhinavDhulipala]

Change the datatype for mem string conversion. The map shouldn't really have ever had int value types as we cast and return a float anyway.

resolves #71

[codeknight03]

What I am concerned about with this change is the main branch worked on one linux system and not on the other, so are we sure changing this is the way to go ?

[abhinavDhulipala]

I'm pretty sure the reason it failed is because the golang type int means different things to different platforms, based in the kernel. But if we use int32/64 or float32/64 golang will make sure to use a consistent underlying data type. Please test out the branch by installing and building the branch.