Added script to generate docs from endpoint help strings.
Added script to generate docs from endpoint help strings.

Invoke this script from anywhere within the mesos source tree
(including in the build directory) to autogenerate documentation for
all endpoint strings and install them into the docs/endpoint folder.
In a subsequent commit we commit all of these autogenerated files back
to the source repo and add a link in home.md to find them.

Review: https://reviews.apache.org/r/43220/

abudnik/mesos,gsantovena/mesos,zmalik/mesos,Gilbert88/mesos,Gilbert88/mesos,neilconway/mesos,dforsyth/mesos,jpeach/mesos,andschwa/mesos,Gilbert88/mesos,abudnik/mesos,reneploetz/mesos,Gilbert88/mesos,kaysoky/mesos,asamerh4/mesos,Gilbert88/mesos,abudnik/mesos,Aman-Jain-14/customizedMesos,Aman-Jain-14/customizedMesos,neilconway/mesos,jpeach/mesos,dforsyth/mesos,craimbert/mesos,reneploetz/mesos,kaysoky/mesos,jpeach/mesos,asamerh4/mesos,kaysoky/mesos,craimbert/mesos,Gilbert88/mesos,neilconway/mesos,dforsyth/mesos,verizonlabs/mesos,asamerh4/mesos,verizonlabs/mesos,andschwa/mesos,andschwa/mesos,andschwa/mesos,gsantovena/mesos,zmalik/mesos,yuquanshan/customizedMesos,reneploetz/mesos,Aman-Jain-14/customizedMesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,neilconway/mesos,kaysoky/mesos,Aman-Jain-14/customizedMesos,jpeach/mesos,dforsyth/mesos,chhsia0/mesos,craimbert/mesos,dforsyth/mesos,dforsyth/mesos,reneploetz/mesos,zmalik/mesos,abudnik/mesos,verizonlabs/mesos,reneploetz/mesos,kaysoky/mesos,yuquanshan/customizedMesos,zmalik/mesos,craimbert/mesos,gsantovena/mesos,dforsyth/mesos,yuquanshan/customizedMesos,verizonlabs/mesos,gsantovena/mesos,asamerh4/mesos,chhsia0/mesos,neilconway/mesos,Gilbert88/mesos,gsantovena/mesos,Aman-Jain-14/customizedMesos,kaysoky/mesos,yuquanshan/customizedMesos,abudnik/mesos,craimbert/mesos,zmalik/mesos,yuquanshan/customizedMesos,asamerh4/mesos,chhsia0/mesos,neilconway/mesos,andschwa/mesos,yuquanshan/customizedMesos,andschwa/mesos,asamerh4/mesos,craimbert/mesos,andschwa/mesos,zmalik/mesos,jpeach/mesos,chhsia0/mesos,abudnik/mesos,verizonlabs/mesos,craimbert/mesos,Aman-Jain-14/customizedMesos,chhsia0/mesos,asamerh4/mesos,chhsia0/mesos,verizonlabs/mesos,neilconway/mesos,kaysoky/mesos,gsantovena/mesos,reneploetz/mesos,chhsia0/mesos,zmalik/mesos,gsantovena/mesos,jpeach/mesos,verizonlabs/mesos,abudnik/mesos,jpeach/mesos,reneploetz/mesos