Add details of the build environment to exodm wiki?

[rsharvey]

It may be appropriate to state what the build tools and environment are for exodm in the wiki? For instance, I started off with OTP 17.4 on Lubuntu 14.04. I nearly just tried it natively on my Mac, but was highly suspicious of that.

It seems that the "regular" build system would be OTP R15B02 on some version of CentOS? At least for 1.3?

[uwiger]

Yes, the version of exodm that GA uses requires OTP R15B02, and the EC2 instance used by GA seems to resemble my CentOS 6.3 64-bit VMWare VM...