Cabinetry

This is a patch release to fix observations for workspaces built with multiple regions (see 90).

**Full list of changes:**
* chore: updating version to 0.1.1 (91)
* fix: observed data in multiple regions (90)
* feat: data/MC ratio plot panel (89)

This release adds a command-line interface to cabinetry. It also enables users to provide custom functions that can be used for template histogram building. See [the documentation](http://cabinetry.readthedocs.io/) for more information on the new functionality.

**Breaking changes:**
* new mandatory `HistogramFolder` option in the config file (see 87)

**Full list of changes:**
* chore: updating version to 0.1.0 (88)
* feat: adding histogram folder to config (87)
* refactor: workspace builder class (84)
* docs: NSF badge in readme (85)
* feat: command-line interface (81)
* feat: always calculate Hessian (83)
* feat: user-defined overrides for template histogram handling (78)
* feat: support fixed parameters (82)
* test: fix issues raised by typeguard (80)

This release adds many features and improvements. They include visualization of pull plots and correlation matrices, more generic systematic uncertainties, and expressions for variables and weights. Type hints are added to the library, and a json schema defines the configuration file structure.

**Full list of changes:**
* chore: updating version to 0.0.5 (79)
* chore: flake8-print checks (77)
* feat: correlation matrix pruning (76)
* refactor: use new pyhf optimizer API (75)
* docs: providing documentation on readthedocs (72)
* feat: expressions for variables and weights (71)
* docs: config schema (70)
* feat: json schema for config (69)
* refactor: two minor updates (68)
* feat: type hints (67)
* feat: generic two-sided systematics (65)
* chore: moving options to setup.cfg (66)
* feat: pull plot (64)
* style: flake8 plugins (63)
* feat: norm factor settings (62)
* feat: more Minuit control and correlation matrix visualization (61)
* refactor: specification of systematics templates (60)
* style: flake8 string fixes (59)
* refactor: f-strings for logging (58)
* refactor: switch to boost-histogram (56)
* docs: update hello world example (55)
* test: integration test (54)
* refactor: uproot4 in contrib (53)
* refactor: boost_histogram for histogramming (50)
* refactor: order of coordinates for templates (49)
* refactor: histogram class (47)
* feat: nll at best-fit point (48)