Fix Numerical Errors; Improve PER

Improvements/Bug Fixes

Misc

PR #131

• fix overflow error in np.exp of SoftmaxPolicy, BoltzmannPolicy by casting to float64 instead of float32
• improve overall np.isfinite asserts
• remove index after reset in *analysis.csv
• remove unused specs
• reorganize and expand test specs
• guard continuous action value range in continuous policies
• fix analytics param variable sourcing

DDPG

PR: #131

• add EpsilonGreedyNoisePolicy

PER

PR: #131

• add memory.update(errors) throughout all agents
• add shape assert for Q values and errors throughout
• auto max_mem_len as max_timestep * max_epis/3 if not specified
• put the missing abs for init reward