Fix bug in merging_statistics.as_cif_block function

[jbeilstenedmands]

Upon iterating through the name dict, the test for finding the string 'percent' should be on the keys, not the values.

Added a line to a test to verify. This issue means that when the merging stats were converted to a cif block, the _reflns.percent_possible_obs item has been in the range 0 -> 1 rather than 0 -> 100 as intended.

[bkpoon]

/azp run Full

[bkpoon]

/azp run Base

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).

[bkpoon]

Looks good to me, thanks!

Can be merged once @rjgildea approves.

[jbeilstenedmands]

@rjgildea just noticed this is still open, care to take a quick look over?