Fix show_pages index api

[AIIX]

• Show Pages index request was simply ignored in the API and always defaulted to activating the first page, instead of the requested index
• Fixes page handling when index is specified along with list of pages in show_pages method call

[codecov]

Codecov Report

Merging #234 (6cdc296) into dev (6ceb058) will increase coverage by 4.46%.
The diff coverage is 43.58%.

@@            Coverage Diff             @@
##              dev     #234      +/-   ##
==========================================
+ Coverage   50.35%   54.81%   +4.46%     
==========================================
  Files         119      156      +37     
  Lines       10077     9318     -759     
==========================================
+ Hits         5074     5108      +34     
+ Misses       5003     4210     -793     

Impacted Files	Coverage Δ
mycroft/audio/__main__.py	0.00% <0.00%> (ø)
mycroft/client/enclosure/__main__.py	0.00% <0.00%> (ø)
mycroft/client/enclosure/mark1/arduino.py	0.00% <0.00%> (ø)
mycroft/client/enclosure/mark1/eyes.py	0.00% <0.00%> (ø)
mycroft/client/enclosure/mark1/mouth.py	0.00% <0.00%> (ø)
mycroft/client/speech/__main__.py	0.00% <0.00%> (ø)
mycroft/client/speech/hotword_factory.py	0.00% <0.00%> (-88.89%)	⬇️
mycroft/client/speech/service.py	0.00% <0.00%> (ø)
mycroft/client/speech/silence.py	0.00% <0.00%> (-42.86%)	⬇️
mycroft/client/text/__init__.py	0.00% <0.00%> (ø)
... and 150 more

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