ISSUE-15 support macos build

[solc42]

Explicit PR for #15

TODO

• flapping test results on macos - seems depends on test execution order, I'll find out and add fix

Started from simple if cfg, but also:

• added few cli tests (for practice purpose and cause there is an issue)
• added headless opt, seemed useful from personal experience and it helped a bit in tests formatting
• changed the way size obtained (see below for details)

About size.

I noticed, that for more ls-like output st_size seems to be valid, cause in some cases actual master-branch behavior looks a bit strange. To get the idea see following examples:

1 For LINUX:

• 1.1 Current master:

 permission | user | group | name       | last-modify                | size
------------+------+-------+------------+----------------------------+------
 drwxr-xr-x | solc | solc  | a_dir_name | 1970-01-01 04:00:10 +03:00 | 4 KB
 -rw-r--r-- | solc | solc  | a_file.txt | 1970-01-01 03:00:10 +03:00 | 4 KB
 drwxr-xr-x | solc | solc  | b_dir_name | 1970-01-01 04:00:10 +03:00 | 4 KB
 -rw-r--r-- | solc | solc  | b_file.txt | 1970-01-01 03:00:10 +03:00 | 4 KB

• 1.2 ls -l:

total 16
drwxr-xr-x 2 solc solc 4096 Jan  1  1970 a_dir_name
-rw-r--r-- 1 solc solc   20 Jan  1  1970 a_file.txt
drwxr-xr-x 2 solc solc 4096 Jan  1  1970 b_dir_name
-rw-r--r-- 1 solc solc   34 Jan  1  1970 b_file.txt

• 1.3 with change to st_size:

 permission | user | group | name       | last-modify                | size
------------+------+-------+------------+----------------------------+------
 drwxr-xr-x | solc | solc  | a_dir_name | 1970-01-01 04:00:10 +03:00 | 4096
 -rw-r--r-- | solc | solc  | a_file.txt | 1970-01-01 03:00:10 +03:00 | 20
 drwxr-xr-x | solc | solc  | b_dir_name | 1970-01-01 04:00:10 +03:00 | 4096
 -rw-r--r-- | solc | solc  | b_file.txt | 1970-01-01 03:00:10 +03:00 | 34

2 For macos:

• 2.1 current master:

 permission | user | group | name       | last-modify                | size
------------+------+-------+------------+----------------------------+------
 drwxr-xr-x | solc | staff | a_dir_name | 1970-01-01 04:00:10 +03:00 | 0 B
 -rw-r--r-- | solc | staff | a_file.txt | 1970-01-01 03:00:10 +03:00 | 4 KB
 drwxr-xr-x | solc | staff | b_dir_name | 1970-01-01 04:00:10 +03:00 | 0 B
 -rw-r--r-- | solc | staff | b_file.txt | 1970-01-01 03:00:10 +03:00 | 4 KB   

• 2.2 ls -l:

total 16
drwxr-xr-x  3 solc  staff  96  1 Jan  1970 a_dir_name
-rw-r--r--  1 solc  staff  20  1 Jan  1970 a_file.txt
drwxr-xr-x  3 solc  staff  96  1 Jan  1970 b_dir_name
-rw-r--r--  1 solc  staff  34  1 Jan  1970 b_file.txt    

• 2.3 with change to st_size:

 permission | user | group | name       | last-modify                | size
------------+------+-------+------------+----------------------------+------
 drwxr-xr-x | solc | staff | a_dir_name | 1970-01-01 04:00:10 +03:00 | 96
 -rw-r--r-- | solc | staff | a_file.txt | 1970-01-01 03:00:10 +03:00 | 20
 drwxr-xr-x | solc | staff | b_dir_name | 1970-01-01 04:00:10 +03:00 | 96
 -rw-r--r-- | solc | staff | b_file.txt | 1970-01-01 03:00:10 +03:00 | 34  

[solc42]

Seems race fixed - narrowing file modification to init once block before all tests.