Throw a more helpful error if py-lmdb out-of-date
Throw a more helpful error if py-lmdb out-of-date

Close #242

gheinrich/DIGITS-GAN,delectable/DIGITS,dongjoon-hyun/DIGITS,batra-mlp-lab/DIGITS,batra-mlp-lab/DIGITS,bygreencn/DIGITS,ZhijieWang/DIGITS,RadicoLabs/DIGITS,TimZaman/DIGITS,AgentVi/DIGITS,Lucaszw/DIGITS,ZhijieWang/DIGITS,TimZaman/DIGITS,brainstorm-ai/DIGITS,ZhijieWang/DIGITS,bygreencn/DIGITS,gheinrich/DIGITS-GAN,dongjoon-hyun/DIGITS,delectable/DIGITS,bygreencn/DIGITS,andreydung/DIGITS,ethantang95/DIGITS-GAN,bygreencn/DIGITS,Deepomatic/DIGITS,rupertsmall/DIGITS,ethantang95/DIGITS-GAN,ethantang95/DIGITS,ethantang95/DIGITS,jmancewicz/DIGITS,Lucaszw/DIGITS,andreydung/DIGITS,dongjoon-hyun/DIGITS,Deepomatic/DIGITS,ethantang95/DIGITS-GAN,AgentVi/DIGITS,andreydung/DIGITS,jmancewicz/DIGITS,batra-mlp-lab/DIGITS,brainstorm-ai/DIGITS,batra-mlp-lab/DIGITS,gheinrich/DIGITS-GAN,RadicoLabs/DIGITS,andreydung/DIGITS,3upperm2n/DIGITS,RadicoLabs/DIGITS,Deepomatic/DIGITS,dongjoon-hyun/DIGITS,Deepomatic/DIGITS,TimZaman/DIGITS,jmancewicz/DIGITS,ethantang95/DIGITS,rupertsmall/DIGITS,gheinrich/DIGITS-GAN,TimZaman/DIGITS,RadicoLabs/DIGITS,AgentVi/DIGITS,AgentVi/DIGITS,ethantang95/DIGITS,rupertsmall/DIGITS,3upperm2n/DIGITS,Lucaszw/DIGITS,brainstorm-ai/DIGITS,delectable/DIGITS,delectable/DIGITS,3upperm2n/DIGITS,jmancewicz/DIGITS,Lucaszw/DIGITS,ZhijieWang/DIGITS,3upperm2n/DIGITS,rupertsmall/DIGITS,ethantang95/DIGITS-GAN,brainstorm-ai/DIGITS