Delete strings.cu, already created 4 of the translation unit

and unrolled functors are scattered across them:
strings_filter.cu, strings_join.cu, strings_sort_device.cu, strings_sort_host.cu, strings_type.h
Merge pull request #30 from AlexeyAB/delete_strings_cu

Delete strings.cu, already created 4 of the translation unit
Fixed a problem with joins on multiple columns
Changed readme
modified reame.md
updated readme.md
updated readme.md file
updated readme file
updated readme
Removed Boost references
Fixed conversion between big endian and little endian.
For speedup sort strings in 8 times for string length: 1/2/4/8 bytes.
By using optimized radix sort for GPU.
Fixed a bug in groupby op. Added support for storing results as binary files.
Speedup of sort strings in 2 - 3.5 times.
For strings length is a multiple of two speedup in 2 - 2.5 times, for multiple of four in 3 - 3.5 times. (Speedup through accelerate of comparison of static strings.)
Merge branch 'master' of github.com:antonmks/Alenka into optimize_sort_strings
Merge pull request #32 from AlexeyAB/optimize_sort_strings

Optimize sort strings (speedup in 2 - 8 times).