Fixing 1201 - array property constraint deserialisation

[conorclifford]

Small fix for #1201 (missing deserialisation of ArrayProperty constraints (minItems, maxItems and uniqueItems).

[fehguy]

@frantuma look OK to you?

[cipresso]

Hi @fehguy. I have the same issue described in #1201 on both 1.5.8 and 1.5.9. I need the fix committed by @conorclifford as I'm deserializing JSON schema that has minItems and maxItems and embedding the resultant Model.

[cipresso]

Hi. I tried out the fix and it works. There's an unnecessary import statement "import com.google.common.collect.Maps;" you might want to remove.

[webron]

@cipresso thanks for validating it.

[blueskyabove27]

I understand that this pull request is the first step to resolving the issue of maxItems within definitions of not being read by swagger-parser (swagger-api/swagger-parser#239). Just wanted to mention that this issue is currently causing our internal code generator (which uses swagger-parser/swagger-core) to not handle this case. Whatever could be done to resolve this we would be most grateful for.