Use property 'number' in JSON Page representation instead of 'page'

[rvervaek]

Fixes gh-237

[codecov]

Codecov Report

Merging #320 into 2.2.x will increase coverage by 0.25%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##              2.2.x     #320      +/-   ##
============================================
+ Coverage     78.84%   79.10%   +0.25%     
  Complexity      396      396              
============================================
  Files            52       52              
  Lines          1541     1541              
  Branches        223      223              
============================================
+ Hits           1215     1219       +4     
+ Misses          233      229       -4     
  Partials         93       93              

Impacted Files	Coverage Δ	Complexity Δ
...ork/cloud/openfeign/support/PageJacksonModule.java	54.16% <ø> (+16.66%)	4.00 <0.00> (ø)