Alibuild

- Now aliBuild gathers usage statistics and reports them to ALICE Offline (full details at https://github.com/alisw/alibuild/blob/master/ANALYTICS.md).
- The command `aliBuild clean [--aggressive-cleanup]` is now able to clean up more unneeded build by-products.
- Improved `aliDoctor <package name>` with human readable output and better indications of what is wrong.
- `aliBuild version` now prints version information.
- Improved development packages mode.
- Improved logs through out the whole build.
- Various cleanups and bug fixes.

- Add alidist hash to analytics (296)
- Improve and refactor aliDoctor (295)

- Fix a problem where in some cases a devel package was not rebuilt as it should (293).
- Polishing Google Analytics documentation (288).
- Various bug fixes and improvements (291, 289).

- Add Google Analytics.
- Improved development mode.
- `aliBuild version` now prints version information.
- Fixed shell detection.
- Improved logs through out the whole aliBuild.
- Various cleanups and bug fixes.

- Do not run the incremental recipe if the first build has failed (174)
- `alienv` complains if attempting to load a non-existing package (237)
- `alienv` prints the just-loaded packages in `enter` and `load` (237)
- Better architecture detection (222)
- Ship `alienv` shell helper with the `pip` distribution (227)
- Detect latest Ubuntu 16.04 and Debian 7/8 (245)

- Do not run the incremental recipe if the first build has failed (174)
- `alienv` complains if attempting to load a non-existing package (237)
- `alienv` prints the just-loaded packages in `enter` and `load` (237)
- Better architecture detection (222)
- Ship `alienv` shell helper with the `pip` distribution (227)