fix pore-size-distribution parser

[ltalirz]

When computing the pore size distribution for a non-porous material, the psd output could contain NaNs, which are not JSON-serializable.

[ltalirz]

@danieleongari fyi - this build on your PR, with some additional modifications. Tests pass - will merge now.

[ltalirz]

release v1.0.1 on its way

[coveralls]

Pull Request Test Coverage Report for Build 280

• 16 of 16 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.5%) to 92.764%

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Totals
Change from base Build 276:	0.5%
Covered Lines:	2064
Relevant Lines:	2225

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💛 - Coveralls