Added Gitter badge
restructure intro

- remove examples for simple object and collection object
- extra section for collections (to be specified)
- remove collection meta properties (they are not as cross-cutting as
the other meta properties, they are quite normal properties)

[ci skip]
basic collection specification
move collections into own group

add some example requests and responses
chose examples matching the response
fix cross ref

[ci skip]
improve wording

[ci skip]
collection-type: "collection" + more clarity

- more concise example-URLS
- explicitly mention "elements" property

[ci skip]
prepend /api/v3

- fewer possibilities to read the URL wrong (op.org/work_packages/1 is
already taken...)
- otherwise it would later become a pain to specify /api/v3 ^^

[ci skip]
equal naming for offset and cursor

[ci skip]
move pagination intro above tables

give some context for words used in the table, real explanation is kept
below the tables

[ci skip]
split that line

[ci skip]
allow nested config env override and addition of new values
don't hardcode ENV as source for config override
more flexible prefix
make sure to only replace an actual prefix
update example links
cleans up variable to hash conversion
Remove various implicit globals in Angular app

This patch does not remove globals used by timelines model: removing
these accidental globals would require addressing a number of
circular dependencies, e.g. between `Timeline` and `Project` objects.

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Fix Karma tests reliant on implicit globals

See a3a07f43.

Signed-off-by: Alex Coles <alex@alexbcoles.com>